Suprametallogels and uses thereof

ABSTRACT

The disclosure provides nanostructures (e.g., nanospheres and nano-paddlewheels) formed through transition metal-ligand (e.g., Pd(II)-, Ni(II)-, or Fe(II)-ligand of Formula (A)) coordination and junction self-assembly. The disclosure also provides supramolecular complexes that include the nanostructures connected by divalent linkers Y. The provided supramolecular complexes are able to form gels (e.g., hydrogels). The gels are suprametallogels and exhibited excellent mechanical properties without sacrificing self-healing and showed high robustness and storage modulus. The present disclosure further provides compositions (e.g., gels) that include the nanostructures or supramolecular complexes and optionally an agent (e.g., small molecule), where the nanostructures and the nanostructure moieties of the supramolecular complexes may encapsulate and slowly release the agent. The nanostructures, supramolecular complex, and compositions may be useful in delivering an agent to a subject, tissue, or cell, as super-absorbent materials, and in treating a disease (e.g., a genetic diseases, proliferative disease (e.g., cancer or benign neoplasm), hematological disease, neurological disease, gastrointestinal disease (e.g., liver disease), spleen disease, respiratory disease (e.g., lung disease), painful condition, genitourinary disease, musculoskeletal condition, infectious disease, inflammatory disease, autoimmune disease, psychiatric disorder, or metabolic disorder).

RELATED APPLICATIONS

The present application is a continuation of and claims priority under35 U.S.C. § 120 to U.S. patent application Ser. No. 14/617,747, filedFeb. 9, 2015, and now issued as U.S. Pat. No. 9,447,129, which claimspriority under 35 U.S.C. § 119(e) to U.S. provisional patentapplication, U.S. Ser. No. 61/937,052, filed Feb. 7, 2014, each of whichis incorporated herein by reference.

GOVERNMENT SUPPORT

This invention was made with Government support under grant numberCHE-1334703 awarded by the National Science Foundation. The Governmenthas certain rights in the invention.

BACKGROUND OF THE INVENTION

Synthetic gels (e.g., synthetic hydrogels) constitute a class ofmaterials useful in biomedicine. One of the first such applications forhydrogels was soft contact lenses invented by Wichterle and Lim. The gelused by Wichterle and Lim was composed of a covalently crosslinkedpoly(hydroxyethyl methacrylate (p(HEMA)). Such covalently-linked gelstypically are typically quite robust but suffer from inability toself-heal when damaged. They also cannot be injected because they don'tflow at relevant timescales, even under a high shear stress.

To complement these materials, metal-ligand coordination-linked gelshave been developed where coordination complexation between metal ionsand ligands were one or the sole crosslinking motif (Holten-Andersen etal., Proceedings of the National Academy of Sciences of the UnitedStates of America, 2011, 108, 2651-2655; Holten-Andersen et al., Journalof Materials Chemistry B, 2014, 2, 2467-2472; Barrett et al., Advancedfunctional materials, 2013, 23, 1111-1119; Fullenkamp et al.,Macromolecules, 2013, 46, 1167-1174; Menyo et al., Soft matter, 2013,9:10314-10323). In particular, much of the work thus far has focusedprimarily on demonstrating the mechanical properties of gels usingdifferent metal-ligand pairs. For example, Fullenkamp et al. studiedhistidine hydrogels with Zn²⁺, Cu²⁺, Co²⁺, and Ni²⁺ as the central atomsin coordination complexes (Fullenkamp et al., Macromolecules, 2013, 46,1167-1174); Holten-Andersen et al. studied 3,4-dihydroxyphenylalanine(DOPA) hydrogels with Fe³⁺, V³⁺, and Al³⁺ the central atoms(Holten-Andersen et al., Journal of Materials Chemistry B, 2014, 2,2467-2472); and Menyo et al. studied hydrogels using DOPA and chemicalmodifications of DOPA using Fe³⁺ as metal centers (Menyo et al., Softmatter, 2013, 9:10314-10323). While these metal-ligandcoordination-linked gels are able to flow at a high shear stress and toself-heal due to the dynamic nature of the coordination bonding, theytypically lack robustness and storage modulus of covalently linked gels.Therefore, there remains a need for new gels with improved properties.

SUMMARY OF THE INVENTION

Synthetic gels are typically formed through the use of strong, staticcovalent bonds or relatively weak, dynamic hydrogen bonds, van derWaals, hydrophobic or ionic interactions, or metal-ligand coordination.Gels formed entirely from the former suffer from an inability toshear-thin or heal upon fracture, while those formed from the latter aregenerally subject to viscous flow even under weak forces. Hierarchicalassembly of multivalent dynamic species within a gel network canpotentially overcome these limitations and introduce novel materialproperties. The present disclosure provides suprametallogels that formvia metallosupramolecular assembly. Compared to conventionalmetallogels, the suprametallogels described herein behave as elasticsolids at low oscillatory angular frequencies and exhibit high storagemoduli. The suprametallogels bridge the gap between traditionalmetallogels and discrete metallosupramolecular assemblies.

In one aspect, the present disclosure provides nanostructures (e.g.,nanospheres (nanocages) and nano-paddlewheels) formed throughmetal-ligand (e.g., transition metal-ligand of Formula (A)) coordinationand junction self-assembly. The present disclosure also providessupramolecular complexes that include nanostructures described hereinconnected by divalent linkers Y. The provided supramolecular complexesare able to swell in various solvents (including water) withoutdissolution and to form a new class of gels, “suprametallogels.” Thegels described herein exhibited better mechanical properties withoutsacrificing self-healing than conventional gels and showed higherrobustness and storage modulus than conventional nanostructures. Thenanostructures, and the nanostructure moieties of a supramolecularcomplex or gel described herein, may encapsulate and slowly release anagent (e.g., a small molecule). The nanostructures, supramolecularcomplex, and compositions (e.g., gels) may be useful in deliveringeffectively and efficiently an agent to a subject, tissue, or cell. Thesupramolecular complexes and compositions (e.g., gels) may also be ableto absorb a large amount of a fluid (e.g., absorb at least 100 times byweight of the fluid, compared to the weight of the supramolecularcomplex or the dry weight of the composition (weight of the compositionminus the weight of the fluid included in the composition) and,therefore, may be useful as super-absorbent materials.

In one aspect, the present disclosure provides nanostructurescomprising:

(i) a plurality of a transition metal ion; and

(ii) a plurality of a ligand;

wherein each instance of the transition metal ion and two or moreinstances of the ligand form through coordination bonds a coordinationcomplex; and

wherein the average outer diameter of the nanostructure is between about1 nm and about 100 nm, inclusive.

In certain embodiments, a nanostructure described herein comprises:

(i) x instances of a transition metal ion, wherein x is an integerbetween 2 and 60, inclusive; and

(ii) 2x instances of a ligand of Formula (A):

wherein:

Ring A is a substituted or unsubstituted phenyl ring or a substituted orunsubstituted, 5- or 6-membered, monocyclic heteroaryl ring;

each instance of X^(A), X^(B), X^(C), and X^(D) is independently O, S,N, NR^(A1), C, or CR^(A2);

X^(E) is absent, N, or CR^(A2);

each instance of R^(A1) is independently hydrogen, substituted orunsubstituted alkyl, substituted or unsubstituted alkenyl, substitutedor unsubstituted alkynyl, substituted or unsubstituted carbocyclyl,substituted or unsubstituted heterocyclyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl, —C(═O)R^(a),—C(═O)OR^(a), —C(═O)N(R^(a))₂, or a nitrogen protecting group;

each instance of R^(A2) is independently hydrogen, halogen, substitutedor unsubstituted alkyl, substituted or unsubstituted alkenyl,substituted or unsubstituted alkynyl, substituted or unsubstitutedcarbocyclyl, substituted or unsubstituted heterocyclyl, substituted orunsubstituted aryl, substituted or unsubstituted heteroaryl, —OR^(a),—N(R^(a))₂, —SR^(a), —CN, —SCN, —C(═NR^(a))R^(a), —C(═NR^(a))OR^(a),—C(═NR^(a))N(R^(a))₂, —C(═O)R^(a), —C(═O)OR^(a), —C(═O)N(R^(a))₂, —NO₂,—NR^(a)C(═O)R^(a), —NR^(a)C(═O)OR^(a), —NR^(a)C(═O)N(R^(a))₂,—OC(═O)R^(a), —OC(═O)OR^(a), or —OC(═O)N(R^(a))₂;

each instance of R^(a) is independently hydrogen, substituted orunsubstituted acyl, substituted or unsubstituted alkyl, substituted orunsubstituted alkenyl, substituted or unsubstituted alkynyl, substitutedor unsubstituted carbocyclyl, substituted or unsubstituted heterocyclyl,substituted or unsubstituted aryl, substituted or unsubstitutedheteroaryl, a nitrogen protecting group when attached to a nitrogenatom, an oxygen protecting group when attached to an oxygen atom, or asulfur protecting group when attached to a sulfur atom, or two instancesof R^(a) are joined to form a substituted or unsubstituted heterocyclicor substituted or unsubstituted heteroaryl ring;

each instance of R^(B) is independently halogen, substituted orunsubstituted alkyl, substituted or unsubstituted alkenyl, substitutedor unsubstituted alkynyl, substituted or unsubstituted carbocyclyl,substituted or unsubstituted heterocyclyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl, —OR^(a), —N(R^(a))₂,—SR^(a), —CN, —SCN, —C(═NR^(a))R^(a), —C(═NR^(a))OR^(a),—C(═NR^(a))N(R^(a))₂, —C(═O)R^(a), —C(═O)OR^(a), —C(═O)N(R^(a))₂, —NO₂,—NR^(a)C(═O)R^(a), —NR^(a)C(═O)OR^(a), —NR^(a)C(═O)N(R^(a))₂,—OC(═O)R^(a), —OC(═O)OR^(a), or —OC(═O)N(R^(a))₂;

m is 0, 1, 2, 3, or 4;

each instance of R^(C) is independently halogen, substituted orunsubstituted alkyl, substituted or unsubstituted alkenyl, substitutedor unsubstituted alkynyl, substituted or unsubstituted carbocyclyl,substituted or unsubstituted heterocyclyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl, —OR^(a), —N(R^(a))₂,—SR^(a), —CN, —SCN, —C(═NR^(a))R^(a), —C(═NR^(a))OR^(a),—C(═NR^(a))N(R^(a))₂, —C(═O)R^(a), —C(═O)OR^(a), —C(═O)N(R^(a))₂, —NO₂,—NR^(a)C(═O)R^(a), —NR^(a)C(═O)OR^(a), —NR^(a)C(═O)N(R^(a))₂,—OC(═O)R^(a), —OC(═O)OR^(a), or —OC(═O)N(R^(a))₂;

n is 0, 1, 2, 3, or 4;

Z^(A) is a bond or a substituted or unsubstituted C₁₋₄ hydrocarbonchain, optionally wherein one or more chain atoms are independentlyreplaced with —O—, —S—, —NR^(ZA)—, —N═, or ═N—, wherein each instance ofR^(ZA) is independently hydrogen, substituted or unsubstituted C₁₋₆alkyl, or a nitrogen protecting group;

Z^(B) is a bond or a substituted or unsubstituted C₁₋₄ hydrocarbonchain, optionally wherein one or more chain atoms are independentlyreplaced with —O—, —S—, or —NR^(ZB)—, wherein each instance of R^(ZB) isindependently hydrogen, substituted or unsubstituted C₁₋₆ alkyl, or anitrogen protecting group;

wherein each instance of the transition metal ion and two instances ofthe ligand of Formula (A) form through coordination bonds a coordinationcomplex;

wherein each of the coordination bonds is formed between an instance ofthe transition metal ion and the nitrogen atom labeled with 1′ or 1″ ofan instance of the ligand of Formula (A);

wherein the x instances of the transition metal ion and the 2x instancesof the ligand of Formula (A) form through the coordination bonds asubstantially spherical or substantially paddlewheel structure; and

wherein the average outer diameter of the nanostructure is between about1 nm and about 100 nm, inclusive.

In certain embodiments, the x instances of the transition metal ion andthe 2x instances of the ligand of Formula (A) form through thecoordination bonds a substantially spherical structure. When the xinstances of the transition metal ion and the 2x instances of the ligandof Formula (A) form through the coordination bonds a substantiallyspherical structure, the nanostructure is a nanosphere. In certainembodiments, the x instances of the transition metal ion and the 2xinstances of the ligand of Formula (A) form through the coordinationbonds a substantially paddlewheel structure. When the x instances of thetransition metal ion and the 2x instances of the ligand of Formula (A)form through the coordination bonds a substantially paddlewheelstructure, the nanostructure is a nano-paddlewheel.

In certain embodiments, the nanosphere has icosidodecahedral symmetry.In certain embodiments, a nanosphere described herein is of Formula(I-A) as shown in FIG. 29, or a salt thereof, wherein each instance ofthe black dot represents the transition metal ion, each instance of thegray line represents the ligand of Formula (A), and each black linerepresents the coordination bond.

In certain embodiments, the nanosphere has icosidodecahedral symmetry.In certain embodiments, a nanosphere described herein is of Formula(I-B) as shown in FIG. 30, or a salt thereof, wherein each instance ofthe black dot represents the transition metal ion, and each instance ofthe gray line represents the ligand of Formula (A).

In another aspect, the present disclosure provides supramolecularcomplexes comprising:

(a) two or more instances of a nanostructure described herein; and

(b) at least one instance of Y, wherein each instance of Y isindependently a substituted or unsubstituted, saturated or unsaturatedC₃₀₋₃₀₀₀ hydrocarbon chain, optionally wherein one or more chain atomsare independently replaced with —O—, —S—, —NR^(Y)—, ═N—, or —N═, whereineach instance of R^(a) is independently hydrogen, substituted orunsubstituted C₁₋₆ alkyl, or a nitrogen protecting group;

wherein each instance of Y is independently directly covalently attachedto an instance of the ligand of Formula (A) and directly covalentlyattached to another instance of the ligand of Formula (A), and at leasttwo instances of the nanostructure are directly covalently connected byat least one instance of Y.

In certain embodiments, a supramolecular complex described herein formsa gel (suprametallogel) upon contact with a fluid (e.g., water). Incertain embodiments, a nanostructure or supramolecular complex describedherein may further comprise at least one instance of an anioniccounterion.

In another aspect, the present disclosure provides methods of preparingthe nanostructures, the methods including reacting a ligand of Formula(A), or a salt thereof, with a transition metal salt.

In another aspect, the present disclosure provides methods of preparingthe supramolecular complexes, the methods including complexing amacromer of Formula (B) or (C), or a salt thereof, with a transitionmetal salt:

in the presence of a fluid and optionally an agent.

The transition metal of the transition metal ion or transition metalsalt may be Pd(II), Ni(II), Fe(II), Rh(I), Ir(I), Pt(II), or Au(III).

In another aspect, the present disclosure provides methods of preparingthe gels, the methods comprising complexing a macromer of Formula (B) or(C) with a transition metal salt in the presence of a fluid andoptionally an agent (i.e., agent to be delivered).

In yet another aspect, the present disclosure provides compositions(e.g., pharmaceutical compositions) comprising a nanostructure orsupramolecular complex described herein, optionally an agent (e.g., asmall molecule), and optionally an excipient (e.g., a pharmaceuticallyacceptable excipient). In certain embodiments, a composition describedherein is in the form of a gel (e.g., hydrogel). The describedcompositions are thought to be useful for delivering an agent to asubject, tissue, or cell. An agent may be encapsulated within thenanostructures or the nanostructure moieties of a supramolecular complexand may get transported through the cell membranes (e.g., into or out ofa cell). The nanostructures or nanostructure moieties of asupramolecular complex may dissociate and release the agent to a cell(e.g., a target cell) or tissue (e.g., a target tissue).

The compositions described herein (e.g., pharmaceutical compositions)may be useful in treating a variety of diseases (e.g., genetic diseases,proliferative diseases (e.g., cancers and benign neoplasms),hematological diseases, neurological diseases, gastrointestinal diseases(e.g., liver diseases), spleen diseases, respiratory diseases (e.g.,lung diseases), painful conditions, genitourinary diseases,musculoskeletal conditions, infectious diseases, inflammatory diseases,autoimmune diseases, psychiatric disorders, and metabolic disorders) ina subject in need thereof. In certain embodiments, a compositiondescribed herein includes a therapeutically effective amount of theagent.

The compositions described herein (e.g., pharmaceutical compositions)may also be useful in preventing a range of diseases (e.g., geneticdiseases, proliferative diseases (e.g., cancers and benign neoplasms),hematological diseases, neurological diseases, gastrointestinal diseases(e.g., liver diseases), spleen diseases, respiratory diseases (e.g.,lung diseases), painful conditions, genitourinary diseases,musculoskeletal conditions, infectious diseases, inflammatory diseases,autoimmune diseases, psychiatric disorders, and metabolic disorders) ina subject. In certain embodiments, a composition described hereinincludes a prophylactically effective amount of the agent.

Another aspect of the present disclosure relates to methods ofdelivering an agent to a subject. In certain embodiments, the method ofdelivering an agent comprises administering to a subject (e.g., a human)a composition (e.g., gel) described herein.

Another aspect of the present disclosure relates to methods ofdelivering an agent to a tissue. In certain embodiments, the method ofdelivering an agent comprises contacting a tissue (e.g., a liver,spleen, or lung) with a composition (e.g., gel) described herein. Incertain embodiments, the agent is selectively delivered to a targettissue, compared to the delivery of the agent to a non-target tissue.For example, the agent may be delivered to a target tissue at 5 times,10 times, 50 times, or 100 times greater than delivery to a non-targettissue.

Another aspect of the present disclosure relates to methods ofdelivering an agent to a cell. In certain embodiments, the method ofdelivering an agent comprises contacting a cell with a composition(e.g., gel) described herein. The cell may be in vitro or in vivo. Incertain embodiments, the agent is selectively delivered to a target cellcompared to the delivery of the agent to a non-target cell.

Another aspect of the disclosure relates to methods of increasing theexposure or concentration of an agent in a subject, tissue, or cell.

In another aspect, the present disclosure provides methods of treating adisease in a subject in need thereof. In certain embodiments, themethods of treating a disease comprise administering to the subject atherapeutically effective amount of a composition described herein.

In still another aspect, the present disclosure provides methods ofpreventing a disease in a subject in need thereof. In certainembodiments, the methods of preventing a disease comprise administeringto the subject a prophylactically effective amount of a compositiondescribed herein.

In certain embodiments, the disease that is treated or prevented by adescribed method is a genetic diseases, proliferative disease (e.g.,cancer or benign neoplasm), hematological disease, neurological disease,gastrointestinal disease (e.g., liver disease), spleen disease,respiratory disease (e.g., lung disease), painful condition,genitourinary disease, musculoskeletal condition, infectious disease,inflammatory disease, autoimmune disease, psychiatric disorder, ormetabolic disorder. In certain embodiments, the disease is hepaticcarcinoma, hypercholesterolemia, refractory anemia, or familial amyloidneuropathy.

In yet another aspect, the present disclosure provides nanostructures,supramolecular complexes, and compositions described herein for use in amethod of the present disclosure (e.g., a method of delivering an agentto a subject; a method of delivering an agent to a tissue; a method ofdelivering an agent to a cell; a method of increasing the exposure orconcentration of an agent in a subject, tissue, or cell; a method oftreating a disease in a subject in need thereof; or a method ofpreventing a disease in a subject).

Another aspect of the present disclosure relates to kits comprising acontainer with: a transition metal salt, ligand of Formula (A), macromerof Formula (B), macromer of Formula (C), nanostructure, supramolecularcomplex, composition described herein, or a combination thereof. Thekits may include a single dose or multiple doses of the nanostructure,supramolecular complex, or composition. The kits may be useful in amethod described herein. In certain embodiments, a kit of the disclosurefurther includes instructions for preparing and/or using the inventivenanostructures, supramolecular complexes, and/or compositions thereof(e.g., for administering the nanostructures, supramolecular complexes,or compositions to a subject (e.g., as required by a regulatoryagency)).

The details of one or more embodiments of the disclosure are set forthherein. Other features, objects, and advantages of the disclosure willbe apparent from the Detailed Description, the Figures, the Examples,and the Claims.

Definitions

Definitions of specific functional groups and chemical terms aredescribed in more detail below. The chemical elements are identified inaccordance with the Periodic Table of the Elements, CAS version,Handbook of Chemistry and Physics, 75^(th) Ed., inside cover, andspecific functional groups are generally defined as described therein.Additionally, general principles of organic chemistry, as well asspecific functional moieties and reactivity, are described in ThomasSorrell, Organic Chemistry, University Science Books, Sausalito, 1999;Smith and March, March's Advanced Organic Chemistry, 5^(th) Edition,John Wiley & Sons, Inc., New York, 2001; Larock, Comprehensive OrganicTransformations, VCH Publishers, Inc., New York, 1989; and Carruthers,Some Modern Methods of Organic Synthesis, 3^(rd) Edition, CambridgeUniversity Press, Cambridge, 1987.

Compounds (e.g., ligands) described herein can comprise one or moreasymmetric centers, and thus can exist in various isomeric forms, e.g.,enantiomers and/or diastereomers. For example, the compounds describedherein can be in the form of an individual enantiomer, diastereomer orgeometric isomer, or can be in the form of a mixture of stereoisomers,including racemic mixtures and mixtures enriched in one or morestereoisomer. Isomers can be isolated from mixtures by methods known tothose skilled in the art, including chiral high pressure liquidchromatography (HPLC) and the formation and crystallization of chiralsalts; or preferred isomers can be prepared by asymmetric syntheses.See, for example, Jacques et al., Enantiomers, Racemates and Resolutions(Wiley Interscience, New York, 1981); Wilen et al., Tetrahedron 33:2725(1977); Eliel, Stereochemistry of Carbon Compounds (McGraw-Hill, N Y,1962); and Wilen, Tables of Resolving Agents and Optical Resolutions p.268 (E. L. Eliel, Ed., Univ. of Notre Dame Press, Notre Dame, Ind.1972). The invention additionally encompasses compounds described hereinas individual isomers substantially free of other isomers, andalternatively, as mixtures of various isomers.

When a range of values is listed, it is intended to encompass each valueand sub-range within the range. For example “C₁₋₆” is intended toencompass, C₁, C₂, C₃, C₄, C₅, C₆, C₁₋₆, C₁₋₅, C₁₋₄, C₁₋₃, C₁₋₂, C₂₋₆,C₂₋₅, C₂₋₄, C₂₋₃, C₃₋₆, C₃₋₅, C₃₋₄, C₄₋₆, C₄₋₅, and C₅₋₆.

The term “aliphatic” refers to alkyl, alkenyl, alkynyl, and carbocyclicgroups. Likewise, the term “heteroaliphatic” refers to heteroalkyl,heteroalkenyl, heteroalkynyl, and heterocyclic groups.

“Alkyl” refers to a radical of a straight-chain or branched saturatedhydrocarbon group having from 1 to 20 carbon atoms (“C₁₋₂₀ alkyl”). Insome embodiments, an alkyl group has 1 to 10 carbon atoms (“C₁₋₁₀alkyl”). In some embodiments, an alkyl group has 1 to 9 carbon atoms(“C₁₋₉ alkyl”). In some embodiments, an alkyl group has 1 to 8 carbonatoms (“C₁₋₈ alkyl”). In some embodiments, an alkyl group has 1 to 7carbon atoms (“C₁₋₇ alkyl”). In some embodiments, an alkyl group has 1to 6 carbon atoms (“C₁₋₆ alkyl”). In some embodiments, an alkyl grouphas 1 to 5 carbon atoms (“C₁₋₅ alkyl”). In some embodiments, an alkylgroup has 1 to 4 carbon atoms (“C₁₋₄ alkyl”). In some embodiments, analkyl group has 1 to 3 carbon atoms (“C₁₋₃ alkyl”). In some embodiments,an alkyl group has 1 to 2 carbon atoms (“C₁₋₂ alkyl”). In someembodiments, an alkyl group has 1 carbon atom (“C₁ alkyl”). In someembodiments, an alkyl group has 2 to 6 carbon atoms (“C₂₋₆ alkyl”).Examples of C₁₋₆ alkyl groups include methyl (C₁), ethyl (C₂), n-propyl(C₃), isopropyl (C₃), n-butyl (C₄), tert-butyl (C₄), sec-butyl (C₄),isobutyl (C₄), n-pentyl (C₅), 3-pentanyl (C₅), amyl (C₅), neopentyl(C₅), 3-methyl-2-butanyl (C₅), tertiary amyl (C₅), and n-hexyl (C₆).Additional examples of alkyl groups include n-heptyl (C₇), n-octyl (C₈),and the like. Unless otherwise specified, each instance of an alkylgroup is independently optionally substituted, i.e., unsubstituted (an“unsubstituted alkyl”) or substituted (a “substituted alkyl”) with oneor more substituents. In certain embodiments, the alkyl group isunsubstituted C₁₋₁₀ alkyl (e.g., —CH₃). In certain embodiments, thealkyl group is substituted C₁₋₁₀ alkyl.

“Alkenyl” refers to a radical of a straight-chain or branchedhydrocarbon group having from 2 to 20 carbon atoms, one or morecarbon-carbon double bonds, and no triple bonds (“C₂₋₂₀ alkenyl”). Insome embodiments, an alkenyl group has 2 to 10 carbon atoms (“C₂₋₁₀alkenyl”). In some embodiments, an alkenyl group has 2 to 9 carbon atoms(“C₂₋₉ alkenyl”). In some embodiments, an alkenyl group has 2 to 8carbon atoms (“C₂₋₈ alkenyl”). In some embodiments, an alkenyl group has2 to 7 carbon atoms (“C₂₋₇ alkenyl”). In some embodiments, an alkenylgroup has 2 to 6 carbon atoms (“C₂₋₆ alkenyl”). In some embodiments, analkenyl group has 2 to 5 carbon atoms (“C₂₋₅ alkenyl”). In someembodiments, an alkenyl group has 2 to 4 carbon atoms (“C₂₋₄ alkenyl”).In some embodiments, an alkenyl group has 2 to 3 carbon atoms (“C₂₋₃alkenyl”). In some embodiments, an alkenyl group has 2 carbon atoms (“C₂alkenyl”). The one or more carbon-carbon double bonds can be internal(such as in 2-butenyl) or terminal (such as in 1-butenyl). Examples ofC₂₋₄ alkenyl groups include ethenyl (C₂), 1-propenyl (C₃), 2-propenyl(C₃), 1-butenyl (C₄), 2-butenyl (C₄), butadienyl (C₄), and the like.Examples of C₂₋₆ alkenyl groups include the aforementioned C₂₋₄ alkenylgroups as well as pentenyl (C₅), pentadienyl (C₅), hexenyl (C₆), and thelike. Additional examples of alkenyl include heptenyl (C₇), octenyl(C₈), octatrienyl (C₈), and the like. Unless otherwise specified, eachinstance of an alkenyl group is independently optionally substituted,i.e., unsubstituted (an “unsubstituted alkenyl”) or substituted (a“substituted alkenyl”) with one or more substituents. In certainembodiments, the alkenyl group is unsubstituted C₂₋₁₀ alkenyl. Incertain embodiments, the alkenyl group is substituted C₂₋₁₀ alkenyl. Inan alkenyl group, a C═C double bond for which the stereochemistry isunspecified

may be an (E)- or (Z)-double bond.

“Alkynyl” refers to a radical of a straight-chain or branchedhydrocarbon group having from 2 to 20 carbon atoms, one or morecarbon-carbon triple bonds, and optionally one or more double bonds(“C₂₋₂₀ alkynyl”). In some embodiments, an alkynyl group has 2 to 10carbon atoms (“C₂₋₁₀ alkynyl”). In some embodiments, an alkynyl grouphas 2 to 9 carbon atoms (“C₂₋₉ alkynyl”). In some embodiments, analkynyl group has 2 to 8 carbon atoms (“C₂₋₈ alkynyl”). In someembodiments, an alkynyl group has 2 to 7 carbon atoms (“C₂₋₇ alkynyl”).In some embodiments, an alkynyl group has 2 to 6 carbon atoms (“C₂₋₆alkynyl”). In some embodiments, an alkynyl group has 2 to 5 carbon atoms(“C₂₋₅ alkynyl”). In some embodiments, an alkynyl group has 2 to 4carbon atoms (“C₂₋₄ alkynyl”). In some embodiments, an alkynyl group has2 to 3 carbon atoms (“C₂₋₃ alkynyl”). In some embodiments, an alkynylgroup has 2 carbon atoms (“C₂ alkynyl”). The one or more carbon-carbontriple bonds can be internal (such as in 2-butynyl) or terminal (such asin 1-butynyl). Examples of C₂₋₄ alkynyl groups include, withoutlimitation, ethynyl (C₂), 1-propynyl (C₃), 2-propynyl (C₃), 1-butynyl(C₄), 2-butynyl (C₄), and the like. Examples of C₂₋₆ alkenyl groupsinclude the aforementioned C₂₋₄ alkynyl groups as well as pentynyl (C₅),hexynyl (C₆), and the like. Additional examples of alkynyl includeheptynyl (C₇), octynyl (C₈), and the like. Unless otherwise specified,each instance of an alkynyl group is independently optionallysubstituted, i.e., unsubstituted (an “unsubstituted alkynyl”) orsubstituted (a “substituted alkynyl”) with one or more substituents. Incertain embodiments, the alkynyl group is unsubstituted C₂₋₁₀ alkynyl.In certain embodiments, the alkynyl group is substituted C₂₋₁₀ alkynyl.

The term “heteroatom” refers to an atom that is not hydrogen or carbon.In certain embodiments, the heteroatom is nitrogen. In certainembodiments, the heteroatom is oxygen. In certain embodiments, theheteroatom is sulfur.

The term “carbocyclyl” or “carbocyclic” refers to a radical of anon-aromatic cyclic hydrocarbon group having from 3 to 14 ring carbonatoms (“C₃₋₁₄ carbocyclyl”) and zero heteroatoms in the non-aromaticring system. In some embodiments, a carbocyclyl group has 3 to 10 ringcarbon atoms (“C₃₋₁₀ carbocyclyl”). In some embodiments, a carbocyclylgroup has 3 to 8 ring carbon atoms (“C₃₋₈ carbocyclyl”). In someembodiments, a carbocyclyl group has 3 to 7 ring carbon atoms (“C₃₋₇carbocyclyl”). In some embodiments, a carbocyclyl group has 3 to 6 ringcarbon atoms (“C₃₋₆ carbocyclyl”). In some embodiments, a carbocyclylgroup has 4 to 6 ring carbon atoms (“C₄₋₆ carbocyclyl”). In someembodiments, a carbocyclyl group has 5 to 6 ring carbon atoms (“C₅₋₆carbocyclyl”). In some embodiments, a carbocyclyl group has 5 to 10 ringcarbon atoms (“C₅₋₁₀ carbocyclyl”). Exemplary C₃₋₆ carbocyclyl groupsinclude, without limitation, cyclopropyl (C₃), cyclopropenyl (C₃),cyclobutyl (C₄), cyclobutenyl (C₄), cyclopentyl (C₅), cyclopentenyl(C₅), cyclohexyl (C₆), cyclohexenyl (C₆), cyclohexadienyl (C₆), and thelike. Exemplary C₃₋₈ carbocyclyl groups include, without limitation, theaforementioned C₃₋₆ carbocyclyl groups as well as cycloheptyl (C₇),cycloheptenyl (C₇), cycloheptadienyl (C₇), cycloheptatrienyl (C₇),cyclooctyl (C₈), cyclooctenyl (C₈), bicyclo[2.2.1]heptanyl (C₇),bicyclo[2.2.2]octanyl (C₈), and the like. Exemplary C₃₋₁₀ carbocyclylgroups include, without limitation, the aforementioned C₃₋₈ carbocyclylgroups as well as cyclononyl (C₉), cyclononenyl (C₉), cyclodecyl (C₁₀),cyclodecenyl (C₁₀), octahydro-1H-indenyl (C₉), decahydronaphthalenyl(C₁₀), spiro[4.5]decanyl (C₁₀), and the like. As the foregoing examplesillustrate, in certain embodiments, the carbocyclyl group is eithermonocyclic (“monocyclic carbocyclyl”) or polycyclic (e.g., containing afused, bridged or spiro ring system such as a bicyclic system (“bicycliccarbocyclyl”) or tricyclic system (“tricyclic carbocyclyl”)) and can besaturated or can contain one or more carbon-carbon double or triplebonds. “Carbocyclyl” also includes ring systems wherein the carbocyclylring, as defined above, is fused with one or more aryl or heteroarylgroups wherein the point of attachment is on the carbocyclyl ring, andin such instances, the number of carbons continue to designate thenumber of carbons in the carbocyclic ring system. Unless otherwisespecified, each instance of a carbocyclyl group is independentlyunsubstituted (an “unsubstituted carbocyclyl”) or substituted (a“substituted carbocyclyl”) with one or more substituents. In certainembodiments, the carbocyclyl group is an unsubstituted C₃₋₁₄carbocyclyl. In certain embodiments, the carbocyclyl group is asubstituted C₃₋₁₄ carbocyclyl.

In some embodiments, “carbocyclyl” is a monocyclic, saturatedcarbocyclyl group having from 3 to 14 ring carbon atoms (“C₃₋₁₄cycloalkyl”). In some embodiments, a cycloalkyl group has 3 to 10 ringcarbon atoms (“C₃₋₁₀ cycloalkyl”). In some embodiments, a cycloalkylgroup has 3 to 8 ring carbon atoms (“C₃₋₈ cycloalkyl”). In someembodiments, a cycloalkyl group has 3 to 6 ring carbon atoms (“C₃₋₆cycloalkyl”). In some embodiments, a cycloalkyl group has 4 to 6 ringcarbon atoms (“C₄₋₆ cycloalkyl”). In some embodiments, a cycloalkylgroup has 5 to 6 ring carbon atoms (“C₅₋₆ cycloalkyl”). In someembodiments, a cycloalkyl group has 5 to 10 ring carbon atoms (“C₅₋₁₀cycloalkyl”). Examples of C₅₋₆ cycloalkyl groups include cyclopentyl(C₅) and cyclohexyl (C₅). Examples of C₃₋₆ cycloalkyl groups include theaforementioned C₅₋₆ cycloalkyl groups as well as cyclopropyl (C₃) andcyclobutyl (C₄). Examples of C₃₋₈ cycloalkyl groups include theaforementioned C₃₋₆ cycloalkyl groups as well as cycloheptyl (C₇) andcyclooctyl (C₈). Unless otherwise specified, each instance of acycloalkyl group is independently unsubstituted (an “unsubstitutedcycloalkyl”) or substituted (a “substituted cycloalkyl”) with one ormore substituents. In certain embodiments, the cycloalkyl group is anunsubstituted C₃₋₁₄ cycloalkyl. In certain embodiments, the cycloalkylgroup is a substituted C₃₋₁₄ cycloalkyl.

“Heterocyclyl” or “heterocyclic” refers to a radical of a 3- to10-membered non-aromatic ring system having ring carbon atoms and 1 to 4ring heteroatoms, wherein each heteroatom is independently selected fromnitrogen, oxygen, sulfur, boron, phosphorus, and silicon (“3-10 memberedheterocyclyl”). In heterocyclyl groups that contain one or more nitrogenatoms, the point of attachment can be a carbon or nitrogen atom, asvalency permits. A heterocyclyl group can either be monocyclic(“monocyclic heterocyclyl”) or a fused, bridged or spiro ring systemsuch as a bicyclic system (“bicyclic heterocyclyl”), and can besaturated or can be partially unsaturated. Heterocyclyl bicyclic ringsystems can include one or more heteroatoms in one or both rings.“Heterocyclyl” also includes ring systems wherein the heterocyclic ring,as defined above, is fused with one or more carbocyclyl groups whereinthe point of attachment is either on the carbocyclyl or heterocyclicring, or ring systems wherein the heterocyclic ring, as defined above,is fused with one or more aryl or heteroaryl groups, wherein the pointof attachment is on the heterocyclic ring, and in such instances, thenumber of ring members continue to designate the number of ring membersin the heterocyclic ring system. Unless otherwise specified, eachinstance of heterocyclyl is independently optionally substituted, i.e.,unsubstituted (an “unsubstituted heterocyclyl”) or substituted (a“substituted heterocyclyl”) with one or more substituents. In certainembodiments, the heterocyclyl group is unsubstituted 3-10 memberedheterocyclyl. In certain embodiments, the heterocyclyl group issubstituted 3-10 membered heterocyclyl.

In some embodiments, a heterocyclyl group is a 5-10 memberednon-aromatic ring system having ring carbon atoms and 1-4 ringheteroatoms, wherein each heteroatom is independently selected fromnitrogen, oxygen, sulfur, boron, phosphorus, and silicon (“5-10 memberedheterocyclyl”). In some embodiments, a heterocyclyl group is a 5-8membered non-aromatic ring system having ring carbon atoms and 1-4 ringheteroatoms, wherein each heteroatom is independently selected fromnitrogen, oxygen, and sulfur (“5-8 membered heterocyclyl”). In someembodiments, a heterocyclyl group is a 5-6 membered non-aromatic ringsystem having ring carbon atoms and 1-4 ring heteroatoms, wherein eachheteroatom is independently selected from nitrogen, oxygen, and sulfur(“5-6 membered heterocyclyl”). In some embodiments, the 5-6 memberedheterocyclyl has 1-3 ring heteroatoms selected from nitrogen, oxygen,and sulfur. In some embodiments, the 5-6 membered heterocyclyl has 1-2ring heteroatoms selected from nitrogen, oxygen, and sulfur. In someembodiments, the 5-6 membered heterocyclyl has one ring heteroatomselected from nitrogen, oxygen, and sulfur.

Exemplary 3-membered heterocyclyl groups containing one heteroatominclude, without limitation, azirdinyl, oxiranyl, and thiiranyl.Exemplary 4-membered heterocyclyl groups containing one heteroatominclude, without limitation, azetidinyl, oxetanyl and thietanyl.Exemplary 5-membered heterocyclyl groups containing one heteroatominclude, without limitation, tetrahydrofuranyl, dihydrofuranyl,tetrahydrothiophenyl, dihydrothiophenyl, pyrrolidinyl, dihydropyrrolyl,and pyrrolyl-2,5-dione. Exemplary 5-membered heterocyclyl groupscontaining two heteroatoms include, without limitation, dioxolanyl,oxasulfuranyl, disulfuranyl, and oxazolidin-2-one. Exemplary 5-memberedheterocyclyl groups containing three heteroatoms include, withoutlimitation, triazolinyl, oxadiazolinyl, and thiadiazolinyl. Exemplary6-membered heterocyclyl groups containing one heteroatom include,without limitation, piperidinyl, tetrahydropyranyl, dihydropyridinyl,and thianyl. Exemplary 6-membered heterocyclyl groups containing twoheteroatoms include, without limitation, piperazinyl, morpholinyl,dithianyl, and dioxanyl. Exemplary 6-membered heterocyclyl groupscontaining two heteroatoms include, without limitation, triazinanyl.Exemplary 7-membered heterocyclyl groups containing one heteroatominclude, without limitation, azepanyl, oxepanyl and thiepanyl. Exemplary8-membered heterocyclyl groups containing one heteroatom include,without limitation, azocanyl, oxecanyl and thiocanyl. Exemplary5-membered heterocyclyl groups fused to a C₆ aryl ring (also referred toherein as a 5,6-bicyclic heterocyclic ring) include, without limitation,indolinyl, isoindolinyl, dihydrobenzofuranyl, dihydrobenzothienyl,benzoxazolinonyl, and the like. Exemplary 6-membered heterocyclyl groupsfused to an aryl ring (also referred to herein as a 6,6-bicyclicheterocyclic ring) include, without limitation, tetrahydroquinolinyl,tetrahydroisoquinolinyl, and the like.

“Aryl” refers to a radical of a monocyclic or polycyclic (e.g., bicyclicor tricyclic) 4n+2 aromatic ring system (e.g., having 6, 10, or 14 pelectrons shared in a cyclic array) having 6-14 ring carbon atoms andzero heteroatoms provided in the aromatic ring system (“C₆₋₁₄ aryl”). Insome embodiments, an aryl group has six ring carbon atoms (“C₆ aryl”;e.g., phenyl). In some embodiments, an aryl group has ten ring carbonatoms (“C₁₀ aryl”; e.g., naphthyl such as 1-naphthyl and 2-naphthyl). Insome embodiments, an aryl group has fourteen ring carbon atoms (“C₁₋₆aryl”; e.g., anthracyl). “Aryl” also includes ring systems wherein thearyl ring, as defined above, is fused with one or more carbocyclyl orheterocyclyl groups wherein the radical or point of attachment is on thearyl ring, and in such instances, the number of carbon atoms continue todesignate the number of carbon atoms in the aryl ring system. Unlessotherwise specified, each instance of an aryl group is independentlyoptionally substituted, i.e., unsubstituted (an “unsubstituted aryl”) orsubstituted (a “substituted aryl”) with one or more substituents. Incertain embodiments, the aryl group is unsubstituted C₆₋₁₄ aryl. Incertain embodiments, the aryl group is substituted C₆₋₁₄ aryl.

“Aralkyl” is a subset of alkyl and aryl and refers to an optionallysubstituted alkyl group substituted by an optionally substituted arylgroup. In certain embodiments, the aralkyl is optionally substitutedbenzyl. In certain embodiments, the aralkyl is benzyl. In certainembodiments, the aralkyl is optionally substituted phenethyl. In certainembodiments, the aralkyl is phenethyl.

“Heteroaryl” refers to a radical of a 5-10 membered monocyclic orbicyclic 4n+2 aromatic ring system (e.g., having 6 or 10 p electronsshared in a cyclic array) having ring carbon atoms and 1-4 ringheteroatoms provided in the aromatic ring system, wherein eachheteroatom is independently selected from nitrogen, oxygen and sulfur(“5-10 membered heteroaryl”). In heteroaryl groups that contain one ormore nitrogen atoms, the point of attachment can be a carbon or nitrogenatom, as valency permits. Heteroaryl bicyclic ring systems can includeone or more heteroatoms in one or both rings. “Heteroaryl” includes ringsystems wherein the heteroaryl ring, as defined above, is fused with oneor more carbocyclyl or heterocyclyl groups wherein the point ofattachment is on the heteroaryl ring, and in such instances, the numberof ring members continue to designate the number of ring members in theheteroaryl ring system. “Heteroaryl” also includes ring systems whereinthe heteroaryl ring, as defined above, is fused with one or more arylgroups wherein the point of attachment is either on the aryl orheteroaryl ring, and in such instances, the number of ring membersdesignates the number of ring members in the fused (aryl/heteroaryl)ring system. Bicyclic heteroaryl groups wherein one ring does notcontain a heteroatom (e.g., indolyl, quinolinyl, carbazolyl, and thelike) the point of attachment can be on either ring, i.e., either thering bearing a heteroatom (e.g., 2-indolyl) or the ring that does notcontain a heteroatom (e.g., 5-indolyl).

In some embodiments, a heteroaryl group is a 5-10 membered aromatic ringsystem having ring carbon atoms and 1-4 ring heteroatoms provided in thearomatic ring system, wherein each heteroatom is independently selectedfrom nitrogen, oxygen, and sulfur (“5-10 membered heteroaryl”). In someembodiments, a heteroaryl group is a 5-8 membered aromatic ring systemhaving ring carbon atoms and 1-4 ring heteroatoms provided in thearomatic ring system, wherein each heteroatom is independently selectedfrom nitrogen, oxygen, and sulfur (“5-8 membered heteroaryl”). In someembodiments, a heteroaryl group is a 5-6 membered aromatic ring systemhaving ring carbon atoms and 1-4 ring heteroatoms provided in thearomatic ring system, wherein each heteroatom is independently selectedfrom nitrogen, oxygen, and sulfur (“5-6 membered heteroaryl”). In someembodiments, the 5-6 membered heteroaryl has 1-3 ring heteroatomsselected from nitrogen, oxygen, and sulfur. In some embodiments, the 5-6membered heteroaryl has 1-2 ring heteroatoms selected from nitrogen,oxygen, and sulfur. In some embodiments, the 5-6 membered heteroaryl has1 ring heteroatom selected from nitrogen, oxygen, and sulfur. Unlessotherwise specified, each instance of a heteroaryl group isindependently optionally substituted, i.e., unsubstituted (an“unsubstituted heteroaryl”) or substituted (a “substituted heteroaryl”)with one or more substituents. In certain embodiments, the heteroarylgroup is unsubstituted 5-14 membered heteroaryl. In certain embodiments,the heteroaryl group is substituted 5-14 membered heteroaryl.

Exemplary 5-membered heteroaryl groups containing one heteroatominclude, without limitation, pyrrolyl, furanyl, and thiophenyl.Exemplary 5-membered heteroaryl groups containing two heteroatomsinclude, without limitation, imidazolyl, pyrazolyl, oxazolyl,isoxazolyl, thiazolyl, and isothiazolyl. Exemplary 5-membered heteroarylgroups containing three heteroatoms include, without limitation,triazolyl, oxadiazolyl, and thiadiazolyl. Exemplary 5-memberedheteroaryl groups containing four heteroatoms include, withoutlimitation, tetrazolyl. Exemplary 6-membered heteroaryl groupscontaining one heteroatom include, without limitation, pyridinyl.Exemplary 6-membered heteroaryl groups containing two heteroatomsinclude, without limitation, pyridazinyl, pyrimidinyl, and pyrazinyl.Exemplary 6-membered heteroaryl groups containing three or fourheteroatoms include, without limitation, triazinyl and tetrazinyl,respectively. Exemplary 7-membered heteroaryl groups containing oneheteroatom include, without limitation, azepinyl, oxepinyl, andthiepinyl. Exemplary 5,6-bicyclic heteroaryl groups include, withoutlimitation, indolyl, isoindolyl, indazolyl, benzotriazolyl,benzothiophenyl, isobenzothiophenyl, benzofuranyl, benzoisofuranyl,benzimidazolyl, benzoxazolyl, benzisoxazolyl, benzoxadiazolyl,benzthiazolyl, benzisothiazolyl, benzthiadiazolyl, indolizinyl, andpurinyl. Exemplary 6,6-bicyclic heteroaryl groups include, withoutlimitation, naphthyridinyl, pteridinyl, quinolinyl, isoquinolinyl,cinnolinyl, quinoxalinyl, phthalazinyl, and quinazolinyl.

“Heteroaralkyl” is a subset of alkyl and heteroaryl and refers to anoptionally substituted alkyl group substituted by an optionallysubstituted heteroaryl group.

“Unsaturated” or “partially unsaturated” refers to a group that includesat least one double or triple bond. A “partially unsaturated” ringsystem is further intended to encompass rings having multiple sites ofunsaturation, but is not intended to include aromatic groups (e.g., arylor heteroaryl groups) as herein defined. Likewise, “saturated” refers toa group that does not contain a double or triple bond, i.e., containsall single bonds.

Alkyl, alkenyl, alkynyl, carbocyclyl, heterocyclyl, aryl, and heteroarylgroups, which are divalent bridging groups are further referred to usingthe suffix -ene, e.g., alkylene, alkenylene, alkynylene, carbocyclylene,heterocyclylene, arylene, and heteroarylene.

The term “optionally substituted” refers to substituted orunsubstituted.

Alkyl, alkenyl, alkynyl, carbocyclyl, heterocyclyl, aryl, and heteroarylgroups are optionally substituted (e.g., “substituted” or“unsubstituted” alkyl, “substituted” or “unsubstituted” alkenyl,“substituted” or “unsubstituted” alkynyl, “substituted” or“unsubstituted” carbocyclyl, “substituted” or “unsubstituted”heterocyclyl, “substituted” or “unsubstituted” aryl or “substituted” or“unsubstituted” heteroaryl group) if not otherwise provided explicitly.In general, the term “substituted”, whether preceded by the term“optionally” or not, means that at least one hydrogen present on a group(e.g., a carbon or nitrogen atom) is replaced with a permissiblesubstituent, e.g., a substituent which upon substitution results in astable compound, e.g., a compound which does not spontaneously undergotransformation such as by rearrangement, cyclization, elimination, orother reaction. Unless otherwise indicated, a “substituted” group has asubstituent at one or more substitutable positions of the group, andwhen more than one position in any given structure is substituted, thesubstituent is either the same or different at each position. The term“substituted” is contemplated to include substitution with allpermissible substituents of organic compounds, any of the substituentsdescribed herein that results in the formation of a stable compound. Thepresent invention contemplates any and all such combinations in order toarrive at a stable compound. For purposes of this invention, heteroatomssuch as nitrogen may have hydrogen substituents and/or any suitablesubstituent as described herein which satisfy the valencies of theheteroatoms and results in the formation of a stable moiety.

Exemplary carbon atom substituents include, but are not limited to,halogen, —CN, —NO₂, —N₃, —SO₂H, —SO₃H, —OH, —OR^(aa), —ON(R^(bb))₂,—N(R^(bb))₂, —N(R^(bb))₃ ⁺X⁻, —N(OR^(cc))R^(bb), —C(═O)R^(aa), —CO₂H,—CHO, —C(OR^(cc))₂, —CO₂R^(aa), —OC(═O)R^(aa), —OCO₂R^(aa),—C(═O)N(R^(bb))₂, —OC(═O)N(R^(bb))₂, —NR^(bb)C(═O)R^(aa),—NR^(bb)CO₂R^(aa), —NR^(bb)C(═O)N(R^(bb))₂, —C(═NR^(bb))R^(aa),—C(═NR^(bb))OR^(aa), —OC(═NR^(bb))R^(aa), —OC(═NR^(bb))OR^(aa),—C(═NR^(bb))N(R^(bb))₂, —OC(═NR^(bb))N(R^(bb))₂,—NR^(bb)C(═NR^(bb))N(R^(bb))₂, —C(═O)NR^(bb)SO₂R, —NR^(bb)SO₂R^(aa),—SO₂N(R^(bb))₂, —SO₂R^(aa), —SO₂OR^(aa), —OSO₂R^(aa), —S(═O)R^(aa),—OS(═O)R^(aa), —Si(R^(aa))₃, —OSi(R^(aa))₃—C(═S)N(R^(bb))₂,—C(═O)SR^(aa), —C(═S)SR^(aa), —SC(═S)SR^(aa), —SC(═O)SR^(aa),—OC(═O)SR^(aa), —SC(═O)OR^(aa), —SC(═O)R^(aa), —P(═O)₂R^(aa),—OP(═O)₂R^(aa), —P(═O)(R^(aa))₂, —OP(═O)(R^(aa))₂, —OP(═O)(OR^(cc))₂,—P(═O)₂N(R^(bb))₂, —OP(═O)₂N(R^(bb))₂, —P(═O)(NR^(bb))₂,—OP(═O)(NR^(bb))₂, —NR^(bb)P(═O)(OR^(cc))₂, —NR^(bb)P(═O)(NR^(bb))₂,—P(R^(cc)) ₂, —P(R^(cc))₃, —OP(R^(cc))₂, —OP(R^(cc))₃, —B(R^(aa))₂,—B(OR^(cc))₂, —BR^(aa)(OR^(cc)), C₁₋ ₁₀ alkyl, C₁₋₁₀ perhaloalkyl, C₂₋₁₀alkenyl, C₂₋₁₀ alkynyl, C₃₋₁₀ carbocyclyl, 3-14 membered heterocyclyl,C₆₋₁₄ aryl, and 5-14 membered heteroaryl, wherein each alkyl, alkenyl,alkynyl, carbocyclyl, heterocyclyl, aryl, and heteroaryl isindependently substituted with 0, 1, 2, 3, 4, or 5 R^(dd) groups; or twogeminal hydrogens on a carbon atom are replaced with the group ═O, ═S,═NN(R^(bb))₂, ═NNR^(bb)C(═O)R^(aa), ═NNR^(bb)C(═O)OR^(aa),═NNR^(bb)S(═O)₂R^(aa), ═NR^(bb), or ═NOR^(cc);

each instance of R^(aa) is, independently, selected from C₁₋₁₀ alkyl,C₁₋₁₀ perhaloalkyl, C₂₋₁₀ alkenyl, C₂₋₁₀ alkynyl, C₃₋₁₀ carbocyclyl,3-14 membered heterocyclyl, C₆₋₁₄ aryl, and 5-14 membered heteroaryl, ortwo R^(aa) groups are joined to form a 3-14 membered heterocyclyl or5-14 membered heteroaryl ring, wherein each alkyl, alkenyl, alkynyl,carbocyclyl, heterocyclyl, aryl, and heteroaryl is independentlysubstituted with 0, 1, 2, 3, 4, or 5 R^(dd) groups;

each instance of R^(bb) is, independently, selected from hydrogen, —OH,—OR^(aa), —N(R^(cc))₂, —CN, —C(═O)R^(aa), —C(═O)N(R^(cc))₂, —CO₂R^(aa),—SO₂R^(aa), —C(═NR^(cc))OR^(aa), —C(═NR^(cc))N(R^(cc))₂, —SO₂N(R^(cc))₂,—SO₂R^(cc), —SO₂OR^(cc), —SOR^(aa), —C(═S)N(R^(cc))₂, —C(═O)SR^(cc),—C(═S)SR^(cc), —P(═O)₂R^(aa), —P(═O)(R^(aa))₂, —P(═O)₂N(R^(cc))₂,—P(═O)(NR^(cc))₂, C₁₋₁₀ alkyl, C₁₋₁₀ perhaloalkyl, C₂₋₁₀ alkenyl, C₂₋₁₀alkynyl, C₃₋₁₀ carbocyclyl, 3-14 membered heterocyclyl, C₆₋₁₄ aryl, and5-14 membered heteroaryl, or two R^(bb) groups are joined to form a 3-14membered heterocyclyl or 5-14 membered heteroaryl ring, wherein eachalkyl, alkenyl, alkynyl, carbocyclyl, heterocyclyl, aryl, and heteroarylis independently substituted with 0, 1, 2, 3, 4, or 5 R^(dd) groups;

each instance of R^(cc) is, independently, selected from hydrogen, C₁₋₁₀alkyl, C₁₋₁₀ perhaloalkyl, C₂₋₁₀ alkenyl, C₂₋₁₀ alkynyl, C₃₋₁₀carbocyclyl, 3-14 membered heterocyclyl, C₆₋₁₄ aryl, and 5-14 memberedheteroaryl, or two R^(cc) groups are joined to form a 3-14 memberedheterocyclyl or 5-14 membered heteroaryl ring, wherein each alkyl,alkenyl, alkynyl, carbocyclyl, heterocyclyl, aryl, and heteroaryl isindependently substituted with 0, 1, 2, 3, 4, or 5 R^(dd) groups;

each instance of R^(dd) is, independently, selected from halogen, —CN,—NO₂, —N₃, —SO₂H, —SO₃H, —OH, —OR^(ee), —ON(R^(ff))₂, —N(R^(ff))₂,—N(R^(ff))₃ ⁺X⁻, —N(OR^(ee))R^(ff), —C(═O)R^(ee), —CO₂H, —CO₂R^(ee),—OC(═O)R^(ee), —OCO₂R^(ee), —C(═O)N(R^(ff))₂, —OC(═O)N(R^(ff))₂,—NR^(ff)C(═O)R^(ee), —NR^(ff)CO₂R^(ee), —NR^(ff)C(═O)N(R^(ff))₂,—C(═NR^(ff))OR^(ee), —OC(═NR^(ff))R^(ee), —OC(═NR^(ff))OR^(ee),—C(═NR^(ff))N(R^(ff))₂, —OC(═NR^(ff))N(R^(ff))₂,—NR^(ff)C(═NR^(ff))N(R^(ff))₂, —NR^(ff)SO₂R^(ee), —SO₂N(R^(ff))₂,—SO₂R^(ee), —SO₂OR^(ee), —OSO₂R^(ee), —S(═O)R^(ee), —Si(R^(ee))₃,—OSi(R^(ee))₃, —C(═S)N(R^(ff))₂, —C(═O)SR^(ee), —C(═S)SR^(ee),—SC(═S)SR^(ee), —P(═O)₂R^(ee), —P(═O)(R^(ee))₂, —OP(═O)(R^(ee))₂,—OP(═O)(OR^(ee))₂, C₁₋₆ alkyl, C₁₋₆ perhaloalkyl, C₂₋₆ alkenyl, C₂₋₆alkynyl, C₃₋₁₀ carbocyclyl, 3-10 membered heterocyclyl, C₆₋₁₀ aryl, 5-10membered heteroaryl, wherein each alkyl, alkenyl, alkynyl, carbocyclyl,heterocyclyl, aryl, and heteroaryl is independently substituted with 0,1, 2, 3, 4, or 5 R^(gg) groups, or two geminal R^(dd) substituents canbe joined to form ═O or ═S;

each instance of R^(ee) is, independently, selected from C₁₋₆ alkyl,C₁₋₆ perhaloalkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₃₋₁₀ carbocyclyl, C₆₋₁₀aryl, 3-10 membered heterocyclyl, and 3-10 membered heteroaryl, whereineach alkyl, alkenyl, alkynyl, carbocyclyl, heterocyclyl, aryl, andheteroaryl is independently substituted with 0, 1, 2, 3, 4, or 5 R^(gg)groups;

each instance of R^(ff) is, independently, selected from hydrogen, C₁₋₆alkyl, C₁₋₆ perhaloalkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₃₋₁₀ carbocyclyl,3-10 membered heterocyclyl, C₆₋₁₀ aryl and 5-10 membered heteroaryl, ortwo R^(ff) groups are joined to form a 3-10 membered heterocyclyl or5-10 membered heteroaryl ring, wherein each alkyl, alkenyl, alkynyl,carbocyclyl, heterocyclyl, aryl, and heteroaryl is independentlysubstituted with 0, 1, 2, 3, 4, or 5 R^(gg) groups; and

each instance of R^(gg) is, independently, halogen, —CN, —NO₂, —N₃,—SO₂H, —SO₃H, —OH, —OC₁₋₆ alkyl, —ON(C₁₋₆ alkyl)₂, —N(C₁₋₆ alkyl)₂,—N(C₁₋₆ alkyl)₃ ⁺X⁻, —NH(C₁₋₆ alkyl)₂ ⁺X⁻, —NH₂(C₁₋₆ alkyl)⁺X⁻, —NH₃⁺X⁻, —N(OC₁₋₆ alkyl)(C₁₋₆ alkyl), —N(OH)(C₁₋₆ alkyl), —NH(OH), —SC₁₋₆alkyl, —SS(C₁₋₆ alkyl), —C(═O)(C₁₋₆ alkyl), —CO₂H, —CO₂(C₁₋₆ alkyl),—OC(═O)(C₁₋₆ alkyl), —OCO₂(C₁₋₆ alkyl), —C(═O)NH₂, —C(═O)N(C₁₋₆ alkyl)₂,—OC(═O)NH(C₁₋₆ alkyl), —NHC(═O)(C₁₋₆ alkyl), —N(C₁₋₆ alkyl)C(═O)(C₁₋₆alkyl), —NHCO₂(C₁₋₆ alkyl), —NHC(═O)N(C₁₋₆ alkyl)₂, —NHC(═O)NH(C₁₋₆alkyl), —NHC(═O)NH₂, —C(═NH)O(C₁₋₆ alkyl), —OC(═NH)(C₁₋₆ alkyl),—OC(═NH)OC₁₋₆ alkyl, —C(═NH)N(C₁₋₆ alkyl)₂, —C(═NH)NH(C₁₋₆ alkyl),—C(═NH)NH₂, —OC(═NH)N(C₁₋₆ alkyl)₂, —OC(NH)NH(C₁₋₆ alkyl), —OC(NH)NH₂,—NHC(NH)N(C₁₋₆ alkyl)₂, —NHC(═NH)NH₂, —NHSO₂(C₁₋₆ alkyl), —SO₂N(C₁₋₆alkyl)₂, —SO₂NH(C₁₋₆ alkyl), —SO₂NH₂, —SO₂C₁₋₆ alkyl, —SO₂OC₁₋₆ alkyl,—OSO₂C₁₋₆ alkyl, —SOC₁₋₆ alkyl, —Si(C₁₋₆ alkyl)₃, —OSi(C₁₋₆ alkyl)₃—C(═S)N(C₁₋₆ alkyl)₂, C(═S)NH(C₁₋₆ alkyl), C(═S)NH₂, —C(═O)S(C₁₋₆alkyl), —C(═S)SC₁₋₆ alkyl, —SC(═S)SC₁₋₆ alkyl, —P(═O)₂(C₁₋₆ alkyl),—P(═O)(C₁₋₆ alkyl)₂, —OP(═O)(C₁₋₆ alkyl)₂, —OP(═O)(OC₁₋₆ alkyl)₂, C₁₋₆alkyl, C₁₋₆ perhaloalkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₃₋₁₀ carbocyclyl,C₆₋₁₀ aryl, 3-10 membered heterocyclyl, 5-10 membered heteroaryl; or twogeminal R^(gg) substituents can be joined to form ═O or ═S; wherein X⁻is a counterion.

“Halo” or “halogen” refers to fluorine (fluoro, —F), chlorine (chloro,—Cl), bromine (bromo, —Br), or iodine (iodo, —I).

“Acyl” refers to a moiety selected from the group consisting of—C(═O)R^(aa), —CHO, —CO₂R^(aa), —C(═O)N(R^(bb))₂, —C(═NR^(bb))R^(aa),—C(═NR^(bb))OR^(aa), —C(═NR^(bb))N(R^(bb))₂, —C(═O)NR^(bb)SO₂R^(aa),—C(═S)N(R^(bb))₂, —C(═O)SR^(aa), or —C(═S)SR^(aa), wherein R^(aa) andR^(bb) are as defined herein.

Nitrogen atoms can be substituted or unsubstituted as valency permits,and include primary, secondary, tertiary, and quaternary nitrogen atoms.Exemplary nitrogen atom substituents include, but are not limited to,hydrogen, —OH, —OR^(aa), —N(R^(cc))₂, —CN, —C(═O)R^(aa),—C(═O)N(R^(cc))₂, —CO₂R^(aa), —SO₂R^(aa), —C(═NR^(bb))R^(aa),—C(═NR^(cc))OR^(aa), —C(═NR^(cc))N(R^(cc))₂, —SO₂N(R^(cc))₂, —SO₂R^(cc),—SO₂OR^(cc), —SOR^(aa), —C(═S)N(R^(cc))₂, —C(═O)SR^(cc), —C(═S)SR^(cc),—P(═O)₂R^(aa), —P(═O)(R^(aa))₂, —P(═O)₂N(R^(cc))₂, —P(═O)(NR^(cc))₂,C₁₋₁₀ alkyl, C₁₋₁₀ perhaloalkyl, C₂₋₁₀ alkenyl, C₂₋₁₀ alkynyl, C₃₋₁₀carbocyclyl, 3-14 membered heterocyclyl, C₆₋₁₄ aryl, and 5-14 memberedheteroaryl, or two R^(cc) groups attached to a nitrogen atom are joinedto form a 3-14 membered heterocyclyl or 5-14 membered heteroaryl ring,wherein each alkyl, alkenyl, alkynyl, carbocyclyl, heterocyclyl, aryl,and heteroaryl is independently substituted with 0, 1, 2, 3, 4, or 5R^(dd) groups, and wherein R^(aa), R^(bb), R^(cc), and R^(dd) are asdefined above.

In certain embodiments, the substituent present on a nitrogen atom is anitrogen protecting group (also referred to as an amino protectinggroup). Nitrogen protecting groups include, but are not limited to, —OH,—OR^(aa), —N(R^(cc))₂, —C(═O)R^(aa), —C(═O)N(R^(cc))₂, —CO₂R^(aa),—SO₂R^(aa), —C(═NR^(cc))R^(aa), —C(═NR^(cc))OR^(aa),—C(═NR^(cc))N(R^(cc))₂, —SO₂N(R^(cc))₂, —SO₂R^(cc), —SO₂OR^(cc),—SOR^(aa), —C(═S)N(R^(cc))₂, —C(═O)SR^(cc), —C(═S)SR^(cc), C₁₋₁₀ alkyl(e.g., aralkyl, heteroaralkyl), C₂₋₁₀ alkenyl, C₂₋₁₀ alkynyl, C₃₋₁₀carbocyclyl, 3-14 membered heterocyclyl, C₆₋₁₄ aryl, and 5-14 memberedheteroaryl groups, wherein each alkyl, alkenyl, alkynyl, carbocyclyl,heterocyclyl, aralkyl, aryl, and heteroaryl is independently substitutedwith 0, 1, 2, 3, 4, or 5 R^(dd) groups, and wherein R^(aa), R^(bb),R^(cc) and R^(dd) are as defined herein. Nitrogen protecting groups arewell known in the art and include those described in detail inProtecting Groups in Organic Synthesis, T. W. Greene and P. G. M. Wuts,3^(rd) edition, John Wiley & Sons, 1999, incorporated herein byreference.

For example, nitrogen protecting groups such as amide groups (e.g.,—C(═O)R^(aa)) include, but are not limited to, formamide, acetamide,chloroacetamide, trichloroacetamide, trifluoroacetamide,phenylacetamide, 3-phenylpropanamide, picolinamide,3-pyridylcarboxamide, N-benzoylphenylalanyl derivative, benzamide,p-phenylbenzamide, o-nitophenylacetamide, o-nitrophenoxyacetamide,acetoacetamide, (N′-dithiobenzyloxyacylamino)acetamide,3-(p-hydroxyphenyl)propanamide, 3-(o-nitrophenyl)propanamide,2-methyl-2-(o-nitrophenoxy)propanamide,2-methyl-2-(o-phenylazophenoxy)propanamide, 4-chlorobutanamide,3-methyl-3-nitrobutanamide, o-nitrocinnamide, N-acetylmethioninederivative, o-nitrobenzamide, and o-(benzoyloxymethyl)benzamide.

Nitrogen protecting groups such as carbamate groups (e.g.,—C(═O)OR^(aa)) include, but are not limited to, methyl carbamate, ethylcarbamante, 9-fluorenylmethyl carbamate (Fmoc),9-(2-sulfo)fluorenylmethyl carbamate, 9-(2,7-dibromo)fluoroenylmethylcarbamate,2,7-di-t-butyl-[9-(10,10-dioxo-10,10,10,10-tetrahydrothioxanthyl)]methylcarbamate (DBD-Tmoc), 4-methoxyphenacyl carbamate (Phenoc),2,2,2-trichloroethyl carbamate (Troc), 2-trimethylsilylethyl carbamate(Teoc), 2-phenylethyl carbamate (hZ), 1-(1-adamantyl)-1-methylethylcarbamate (Adpoc), 1,1-dimethyl-2-haloethyl carbamate,1,1-dimethyl-2,2-dibromoethyl carbamate (DB-t-BOC),1,1-dimethyl-2,2,2-trichloroethyl carbamate (TCBOC),1-methyl-1-(4-biphenylyl)ethyl carbamate (Bpoc),1-(3,5-di-t-butylphenyl)-1-methylethyl carbamate (t-Bumeoc), 2-(2′- and4′-pyridyl)ethyl carbamate (Pyoc), 2-(N,N-dicyclohexylcarboxamido)ethylcarbamate, t-butyl carbamate (BOC or Boc), 1-adamantyl carbamate (Adoc),vinyl carbamate (Voc), allyl carbamate (Alloc), 1-isopropylallylcarbamate (Ipaoc), cinnamyl carbamate (Coc), 4-nitrocinnamyl carbamate(Noc), 8-quinolyl carbamate, N-hydroxypiperidinyl carbamate, alkyldithiocarbamate, benzyl carbamate (Cbz), p-methoxybenzyl carbamate (Moz),p-nitobenzyl carbamate, p-bromobenzyl carbamate, p-chlorobenzylcarbamate, 2,4-dichlorobenzyl carbamate, 4-methylsulfinylbenzylcarbamate (Msz), 9-anthrylmethyl carbamate, diphenylmethyl carbamate,2-methylthioethyl carbamate, 2-methylsulfonylethyl carbamate,2-(p-toluenesulfonyl)ethyl carbamate, [2-(1,3-dithianyl)]methylcarbamate (Dmoc), 4-methylthiophenyl carbamate (Mtpc),2,4-dimethylthiophenyl carbamate (Bmpc), 2-phosphonioethyl carbamate(Peoc), 2-triphenylphosphonioisopropyl carbamate (Ppoc),1,1-dimethyl-2-cyanoethyl carbamate, m-chloro-p-acyloxybenzyl carbamate,p-(dihydroxyboryl)benzyl carbamate, 5-benzisoxazolylmethyl carbamate,2-(trifluoromethyl)-6-chromonylmethyl carbamate (Tcroc), m-nitrophenylcarbamate, 3,5-dimethoxybenzyl carbamate, o-nitrobenzyl carbamate,3,4-dimethoxy-6-nitrobenzyl carbamate, phenyl(o-nitrophenyl)methylcarbamate, t-amyl carbamate, S-benzyl thiocarbamate, p-cyanobenzylcarbamate, cyclobutyl carbamate, cyclohexyl carbamate, cyclopentylcarbamate, cyclopropylmethyl carbamate, p-decyloxybenzyl carbamate,2,2-dimethoxyacylvinyl carbamate, o-(N,N-dimethylcarboxamido)benzylcarbamate, 1,1-dimethyl-3-(N,N-dimethylcarboxamido)propyl carbamate,1,1-dimethylpropynyl carbamate, di(2-pyridyl)methyl carbamate,2-furanylmethyl carbamate, 2-iodoethyl carbamate, isoborynl carbamate,isobutyl carbamate, isonicotinyl carbamate,p-(p′-methoxyphenylazo)benzylcarbamate, 1-methylcyclobutyl carbamate, 1-methylcyclohexyl carbamate,1-methyl-1-cyclopropylmethyl carbamate,1-methyl-1-(3,5-dimethoxyphenyl)ethyl carbamate,1-methyl-1-(p-phenylazophenyl)ethyl carbamate, 1-methyl-1-phenylethylcarbamate, 1-methyl-1-(4-pyridyl)ethyl carbamate, phenyl carbamate,p-(phenylazo)benzyl carbamate, 2,4,6-tri-t-butylphenyl carbamate,4-(trimethylammonium)benzyl carbamate, and 2,4,6-trimethylbenzylcarbamate.

Nitrogen protecting groups such as sulfonamide groups (e.g.,—S(═O)₂R^(aa)) include, but are not limited to, p-toluenesulfonamide(Ts), benzenesulfonamide, 2,3,6,-trimethyl-4-methoxybenzenesulfonamide(Mtr), 2,4,6-trimethoxybenzenesulfonamide (Mtb),2,6-dimethyl-4-methoxybenzenesulfonamide (Pme),2,3,5,6-tetramethyl-4-methoxybenzenesulfonamide (Mte),4-methoxybenzenesulfonamide (Mbs), 2,4,6-trimethylbenzenesulfonamide(Mts), 2,6-dimethoxy-4-methylbenzenesulfonamide (iMds),2,2,5,7,8-pentamethylchroman-6-sulfonamide (Pmc), methanesulfonamide(Ms), β-trimethylsilylethanesulfonamide (SES), 9-anthracenesulfonamide,4-(4′,8′-dimethoxynaphthylmethyl)benzenesulfonamide (DNMBS),benzylsulfonamide, trifluoromethylsulfonamide, and phenacylsulfonamide.

Other nitrogen protecting groups include, but are not limited to,phenothiazinyl-(10)-acyl derivative, N′-p-toluenesulfonylaminoacylderivative, N′-phenylaminothioacyl derivative, N-benzoylphenylalanylderivative, N-acetylmethionine derivative,4,5-diphenyl-3-oxazolin-2-one, N-phthalimide, N-dithiasuccinimide (Dts),N-2,3-diphenylmaleimide, N-2,5-dimethylpyrrole,N-1,1,4,4-tetramethyldisilylazacyclopentane adduct (STABASE),5-substituted 1,3-dimethyl-1,3,5-triazacyclohexan-2-one, 5-substituted1,3-dibenzyl-1,3,5-triazacyclohexan-2-one, 1-substituted3,5-dinitro-4-pyridone, N-methylamine, N-allylamine,N-[2-(trimethylsilyl)ethoxy]methylamine (SEM), N-3-acetoxypropylamine,N-(1-isopropyl-4-nitro-2-oxo-3-pyroolin-3-yl)amine, quaternary ammoniumsalts, N-benzylamine, N-di(4-methoxyphenyl)methylamine,N-5-dibenzosuberylamine, N-triphenylmethylamine (Tr),N-[(4-methoxyphenyl)diphenylmethyl]amine (MMTr),N-9-phenylfluorenylamine (PhF),N-2,7-dichloro-9-fluorenylmethyleneamine, N-ferrocenylmethylamino (Fcm),N-2-picolylamino N′-oxide, N-1,1-dimethylthiomethyleneamine,N-benzylideneamine, N-p-methoxybenzylideneamine,N-diphenylmethyleneamine, N-[(2-pyridyl)mesityl]methyleneamine,N—(N′,N′-dimethylaminomethylene)amine, N,N′-isopropylidenediamine,N-p-nitrobenzylideneamine, N-salicylideneamine,N-5-chlorosalicylideneamine,N-(5-chloro-2-hydroxyphenyl)phenylmethyleneamine,N-cyclohexylideneamine, N-(5,5-dimethyl-3-oxo-1-cyclohexenyl)amine,N-borane derivative, N-diphenylborinic acid derivative,N-[phenyl(pentaacylchromium- or tungsten)acyl]amine, N-copper chelate,N-zinc chelate, N-nitroamine, N-nitrosoamine, amine N-oxide,diphenylphosphinamide (Dpp), dimethylthiophosphinamide (Mpt),diphenylthiophosphinamide (Ppt), dialkyl phosphoramidates, dibenzylphosphoramidate, diphenyl phosphoramidate, benzenesulfenamide,o-nitrobenzenesulfenamide (Nps), 2,4-dinitrobenzenesulfenamide,pentachlorobenzenesulfenamide, 2-nitro-4-methoxybenzenesulfenamide,triphenylmethylsulfenamide, and 3-nitropyridinesulfenamide (Npys).

In certain embodiments, the substituent present on an oxygen atom is anoxygen protecting group (also referred to as a hydroxyl protectinggroup). Oxygen protecting groups include, but are not limited to,—R^(aa), —N(R^(bb))₂, —C(═O)SR^(aa), —C(═O)R^(aa), —CO₂R^(aa),—C(═O)N(R^(bb))₂, —C(═NR^(bb))R^(aa), —C(═NR^(bb))OR^(aa),—C(═NR^(bb))N(R^(bb))₂, —S(═O)R^(aa), —SO₂R^(aa), —Si(R^(aa))₃,—P(R^(cc))₂, —P(R^(cc))₃, —P(═O)₂R^(aa), —P(═O)(R^(aa))₂,—P(═O)(OR^(cc))₂, —P(═O)₂N(R^(bb))₂, and —P(═O)(NR^(bb))₂, whereinR^(aa), R^(bb), and R^(cc) are as defined herein. Oxygen protectinggroups are well known in the art and include those described in detailin Protecting Groups in Organic Synthesis, T. W. Greene and P. G. M.Wuts, 3^(rd) edition, John Wiley & Sons, 1999, incorporated herein byreference.

Exemplary oxygen protecting groups include, but are not limited to,methyl, methoxylmethyl (MOM), tert-butoxycarbonyl, methylthiomethyl(MTM), t-butylthiomethyl, (phenyldimethylsilyl)methoxymethyl (SMOM),benzyloxymethyl (BOM), p-methoxybenzyloxymethyl (PMBM),(4-methoxyphenoxy)methyl (p-AOM), guaiacolmethyl (GUM), t-butoxymethyl,4-pentenyloxymethyl (POM), siloxymethyl, 2-methoxyethoxymethyl (MEM),2,2,2-trichloroethoxymethyl, bis(2-chloroethoxy)methyl,2-(trimethylsilyl)ethoxymethyl (SEMOR), tetrahydropyranyl (THP),3-bromotetrahydropyranyl, tetrahydrothiopyranyl, 1-methoxycyclohexyl,4-methoxytetrahydropyranyl (MTHP), 4-methoxytetrahydrothiopyranyl,4-methoxytetrahydrothiopyranyl S,S-dioxide,1-[(2-chloro-4-methyl)phenyl]-4-methoxypiperidin-4-yl (CTMP),1,4-dioxan-2-yl, tetrahydrofuranyl, tetrahydrothiofuranyl,2,3,3a,4,5,6,7,7a-octahydro-7,8,8-trimethyl-4,7-methanobenzofuran-2-yl,1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, 1-methyl-1-methoxyethyl,1-methyl-1-benzyloxyethyl, 1-methyl-1-benzyloxy-2-fluoroethyl,2,2,2-trichloroethyl, 2-trimethylsilylethyl, 2-(phenylselenyl)ethyl,t-butyl, allyl, p-chlorophenyl, p-methoxyphenyl, 2,4-dinitrophenyl,benzyl (Bn), p-methoxybenzyl, 3,4-dimethoxybenzyl, o-nitrobenzyl,p-nitrobenzyl, p-halobenzyl, 2,6-dichlorobenzyl, p-cyanobenzyl,p-phenylbenzyl, 2-picolyl, 4-picolyl, 3-methyl-2-picolyl N-oxido,diphenylmethyl, p,p′-dinitrobenzhydryl, 5-dibenzosuberyl,triphenylmethyl, α-naphthyldiphenylmethyl,p-methoxyphenyldiphenylmethyl, di(p-methoxyphenyl)phenylmethyl,tri(p-methoxyphenyl)methyl, 4-(4′-bromophenacyloxyphenyl)diphenylmethyl,4,4′,4″-tris(4,5-dichlorophthalimidophenyl)methyl,4,4′,4″-tris(levulinoyloxyphenyl)methyl,4,4′,4″-tris(benzoyloxyphenyl)methyl,3-(imidazol-1-yl)bis(4′,4″-dimethoxyphenyl)methyl,1,1-bis(4-methoxyphenyl)-1′-pyrenylmethyl, 9-anthryl,9-(9-phenyl)xanthenyl, 9-(9-phenyl-10-oxo)anthryl,1,3-benzodisulfuran-2-yl, benzisothiazolyl S,S-dioxido, trimethylsilyl(TMS), triethylsilyl (TES), triisopropylsilyl (TIPS),dimethylisopropylsilyl (IPDMS), diethylisopropylsilyl (DEIPS),dimethylthexylsilyl, t-butyldimethylsilyl (TBDMS), t-butyldiphenylsilyl(TBDPS), tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl,diphenylmethylsilyl (DPMS), t-butylmethoxyphenylsilyl (TBMPS), formate,benzoylformate, acetate, chloroacetate, dichloroacetate,trichloroacetate, trifluoroacetate, methoxyacetate,triphenylmethoxyacetate, phenoxyacetate, p-chlorophenoxyacetate,3-phenylpropionate, 4-oxopentanoate (levulinate),4,4-(ethylenedithio)pentanoate (levulinoyldithioacetal), pivaloate,adamantoate, crotonate, 4-methoxycrotonate, benzoate, p-phenylbenzoate,2,4,6-trimethylbenzoate (mesitoate), alkyl methyl carbonate,9-fluorenylmethyl carbonate (Fmoc), alkyl ethyl carbonate, alkyl2,2,2-trichloroethyl carbonate (Troc), 2-(trimethylsilyl)ethyl carbonate(TMSEC), 2-(phenylsulfonyl) ethyl carbonate (Psec),2-(triphenylphosphonio) ethyl carbonate (Peoc), alkyl isobutylcarbonate, alkyl vinyl carbonate, alkyl allyl carbonate, alkylp-nitrophenyl carbonate, alkyl benzyl carbonate, alkyl p-methoxybenzylcarbonate, alkyl 3,4-dimethoxybenzyl carbonate, alkyl o-nitrobenzylcarbonate, alkyl p-nitrobenzyl carbonate, alkyl S-benzyl thiocarbonate,4-ethoxy-1-napththyl carbonate, methyl dithiocarbonate, 2-iodobenzoate,4-azidobutyrate, 4-nitro-4-methylpentanoate, o-(dibromomethyl)benzoate,2-formylbenzenesulfonate, 2-(methylthiomethoxy)ethyl,4-(methylthiomethoxy)butyrate, 2-(methylthiomethoxymethyl)benzoate,2,6-dichloro-4-methylphenoxyacetate,2,6-dichloro-4-(1,1,3,3-tetramethylbutyl)phenoxyacetate,2,4-bis(1,1-dimethylpropyl)phenoxyacetate, chlorodiphenylacetate,isobutyrate, monosuccinoate, (E)-2-methyl-2-butenoate,o-(methoxyacyl)benzoate, α-naphthoate, nitrate, alkylN,N,N′,N′-tetramethylphosphorodiamidate, alkyl N-phenylcarbamate,borate, dimethylphosphinothioyl, alkyl 2,4-dinitrophenylsulfenate,sulfate, methanesulfonate (mesylate), benzylsulfonate, and tosylate(Ts).

A “hydrocarbon chain” refers to a substituted or unsubstituted divalentalkyl, alkenyl, or alkynyl group. A hydrocarbon chain includes (1) oneor more chains of carbon atoms immediately between the two radicals ofthe hydrocarbon chain; (2) optionally one or more hydrogen atoms on thechain(s) of carbon atoms; and (3) optionally one or more substituents(“non-chain substituents,” which are not hydrogen) on the chain(s) ofcarbon atoms. A chain of carbon atoms consists of consecutivelyconnected carbon atoms (“chain atoms”) and does not include hydrogenatoms or heteroatoms. However, a non-chain substituent of a hydrocarbonchain may include any atoms, including hydrogen atoms, carbon atoms, andheteroatoms. For example, hydrocarbon chain —C^(A)H(C^(B)H₂C^(C)H₃)—includes one chain atom C^(A), one hydrogen atom on C^(A), and non-chainsubstituent —(C^(B)H₂C^(C)H₃). The term “C_(x) hydrocarbon chain,”wherein x is a positive integer, refers to a hydrocarbon chain thatincludes x number of chain atom(s) between the two radicals of thehydrocarbon chain. If there is more than one possible value of x, thesmallest possible value of x is used for the definition of thehydrocarbon chain. For example, —CH(C₂H₅)— is a C₁ hydrocarbon chain,and

is a C₃ hydrocarbon chain. When a range of values is used, the meaningof the range is as described herein. For example, a C₃₋₁₀ hydrocarbonchain refers to a hydrocarbon chain where the number of chain atoms ofthe shortest chain of carbon atoms immediately between the two radicalsof the hydrocarbon chain is 3, 4, 5, 6, 7, 8, 9, or 10. A hydrocarbonchain may be saturated (e.g., —(CH₂)₄—). A hydrocarbon chain may also beunsaturated and include one or more C═C and/or C≡C bonds anywhere in thehydrocarbon chain. For instance, —CH═CH—(CH₂)₂—, —CH₂—C≡C—CH₂—, and—C≡C—CH═CH— are all examples of a unsubstituted and unsaturatedhydrocarbon chain. In certain embodiments, the hydrocarbon chain isunsubstituted (e.g., —C≡C— or —(CH₂)₄—). In certain embodiments, thehydrocarbon chain is substituted (e.g., —CH(C₂H₅)— and —CF₂—). Any twosubstituents on the hydrocarbon chain may be joined to form anoptionally substituted carbocyclyl, optionally substituted heterocyclyl,optionally substituted aryl, or optionally substituted heteroaryl ring.For instance,

are all examples of a hydrocarbon chain. In contrast, in certainembodiments,

are not within the scope of the hydrocarbon chains described herein.When a chain atom of a C_(x) hydrocarbon chain is replaced with aheteroatom, the resulting group is referred to as a C_(x) hydrocarbonchain wherein a chain atom is replaced with a heteroatom, as opposed toa C_(x-1) hydrocarbon chain. For example,

is a C₃ hydrocarbon chain wherein one chain atom is replaced with anoxygen atom.

The term “salt” refers to ionic compounds that result from theneutralization reaction of an acid and a base. A salt is composed of oneor more cations (positively charged ions) and one or more anions(negative ions) so that the salt is electrically neutral (without a netcharge). Salts of the compounds of this invention include those derivedfrom inorganic and organic acids and bases. Examples of acid additionsalts are salts of an amino group formed with inorganic acids such ashydrochloric acid, hydrobromic acid, phosphoric acid, sulfuric acid, andperchloric acid, or with organic acids such as acetic acid, oxalic acid,maleic acid, tartaric acid, citric acid, succinic acid, or malonic acidor by using other methods known in the art such as ion exchange. Othersalts include adipate, alginate, ascorbate, aspartate, benzenesulfonate,benzoate, bisulfate, borate, butyrate, camphorate, camphorsulfonate,citrate, cyclopentanepropionate, digluconate, dodecylsulfate,ethanesulfonate, formate, fumarate, glucoheptonate, glycerophosphate,gluconate, hemisulfate, heptanoate, hexanoate, hydroiodide,2-hydroxy-ethanesulfonate, lactobionate, lactate, laurate, laurylsulfate, malate, maleate, malonate, methanesulfonate,2-naphthalenesulfonate, nicotinate, nitrate, oleate, oxalate, palmitate,pamoate, pectinate, persulfate, 3-phenylpropionate, phosphate, picrate,pivalate, propionate, stearate, succinate, sulfate, tartrate,thiocyanate, p-toluenesulfonate, undecanoate, valerate salts, and thelike. Salts derived from appropriate bases include alkali metal,alkaline earth metal, ammonium and N⁺(C₁₋₄ alkyl)₄ salts. Representativealkali or alkaline earth metal salts include sodium, lithium, potassium,calcium, magnesium, and the like. Further salts include ammonium,quaternary ammonium, and amine cations formed using counterions such ashalide, hydroxide, carboxylate, sulfate, phosphate, nitrate, lower alkylsulfonate, and aryl sulfonate.

The term “pharmaceutically acceptable salt” refers to those salts whichare, within the scope of sound medical judgment, suitable for use incontact with the tissues of humans and lower animals without unduetoxicity, irritation, allergic response, and the like, and arecommensurate with a reasonable benefit/risk ratio. Pharmaceuticallyacceptable salts are well known in the art. For example, Berge et al.,describe pharmaceutically acceptable salts in detail in J.Pharmaceutical Sciences, 1977, 66, 1-19, incorporated herein byreference. Pharmaceutically acceptable salts of the compounds of thisdisclosure include those derived from suitable inorganic and organicacids and bases. Examples of pharmaceutically acceptable, nontoxic acidaddition salts are salts of an amino group formed with inorganic acidssuch as hydrochloric acid, hydrobromic acid, phosphoric acid, sulfuricacid, and perchloric acid or with organic acids such as acetic acid,oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, ormalonic acid or by using other methods known in the art such as ionexchange. Other pharmaceutically acceptable salts include adipate,alginate, ascorbate, aspartate, benzenesulfonate, benzoate, bisulfate,borate, butyrate, camphorate, camphorsulfonate, citrate,cyclopentanepropionate, digluconate, dodecylsulfate, ethanesulfonate,formate, fumarate, glucoheptonate, glycerophosphate, gluconate,hemisulfate, heptanoate, hexanoate, hydroiodide,2-hydroxy-ethanesulfonate, lactobionate, lactate, laurate, laurylsulfate, malate, maleate, malonate, methanesulfonate,2-naphthalenesulfonate, nicotinate, nitrate, oleate, oxalate, palmitate,pamoate, pectinate, persulfate, 3-phenylpropionate, phosphate, picrate,pivalate, propionate, stearate, succinate, sulfate, tartrate,thiocyanate, p-toluenesulfonate, undecanoate, valerate salts, and thelike. Salts derived from appropriate bases include alkali metal,alkaline earth metal, ammonium and N⁺(C₁₋₄ alkyl)₄ ⁻ salts.Representative alkali or alkaline earth metal salts include sodium,lithium, potassium, calcium, magnesium, and the like. Furtherpharmaceutically acceptable salts include, when appropriate, nontoxicammonium, quaternary ammonium, and amine cations formed usingcounterions such as halide, hydroxide, carboxylate, sulfate, phosphate,nitrate, lower alkyl sulfonate, and aryl sulfonate.

The term “solvate” refers to forms of the compound that are associatedwith a solvent, usually by a solvolysis reaction. This physicalassociation may include hydrogen bonding. Conventional solvents includewater, methanol, ethanol, acetic acid, DMSO, THF, diethyl ether, and thelike. Suitable solvates include pharmaceutically acceptable solvates andfurther include both stoichiometric solvates and non-stoichiometricsolvates. In certain instances, the solvate will be capable ofisolation, for example, when one or more solvent molecules areincorporated in the crystal lattice of a crystalline solid. “Solvate”encompasses both solution-phase and isolable solvates. Representativesolvates include hydrates, ethanolates, and methanolates.

The term “hydrate” refers to a compound that is associated with water.Typically, the number of the water molecules contained in a hydrate of acompound is in a definite ratio to the number of the compound moleculesin the hydrate. Therefore, a hydrate of a compound may be represented,for example, by the general formula R·y H₂O, wherein R is the compoundand wherein y is a number greater than 0. A given compound may form morethan one type of hydrates, including, e.g., monohydrates (y is 1), lowerhydrates (y is a number greater than 0 and smaller than 1, e.g.,hemihydrates (R·0.5 H₂O)), and polyhydrates (y is a number greater than1, e.g., dihydrates (R·2 H₂O) and hexahydrates (R·6 H₂O)).

The term “tautomers” refer to compounds that are interchangeable formsof a particular compound structure, and that vary in the displacement ofhydrogen atoms and electrons. Thus, two structures may be in equilibriumthrough the movement of π electrons and an atom (usually H). Forexample, enols and ketones are tautomers because they are rapidlyinterconverted by treatment with either acid or base. Another example oftautomerism is the aci- and nitro-forms of phenylnitromethane, that arelikewise formed by treatment with acid or base.

Tautomeric forms may be relevant to the attainment of the optimalchemical reactivity and biological activity of a compound of interest.

It is also to be understood that compounds that have the same molecularformula but differ in the nature or sequence of bonding of their atomsor the arrangement of their atoms in space are termed “isomers”. Isomersthat differ in the arrangement of their atoms in space are termed“stereoisomers”.

Stereoisomers that are not mirror images of one another are termed“diastereomers” and those that are non-superimposable mirror images ofeach other are termed “enantiomers”. When a compound has an asymmetriccenter, for example, it is bonded to four different groups, a pair ofenantiomers is possible. An enantiomer can be characterized by theabsolute configuration of its asymmetric center and is described by theR- and S-sequencing rules of Cahn and Prelog, or by the manner in whichthe molecule rotates the plane of polarized light and designated asdextrorotatory or levorotatory (i.e., as (+) or (−)-isomersrespectively). A chiral compound can exist as either individualenantiomer or as a mixture thereof. A mixture containing equalproportions of the enantiomers is called a “racemic mixture”.

The term “polymorphs” refers to a crystalline form of a compound (or asalt, hydrate, or solvate thereof) in a particular crystal packingarrangement. All polymorphs have the same elemental composition.Different crystalline forms usually have different X-ray diffractionpatterns, infrared spectra, melting points, density, hardness, crystalshape, optical and electrical properties, stability, and solubility.Recrystallization solvent, rate of crystallization, storage temperature,and other factors may cause one crystal form to dominate. Variouspolymorphs of a compound can be prepared by crystallization underdifferent conditions.

The term “prodrugs” refer to compounds which have cleavable groups andbecome by solvolysis or under physiological conditions the compoundsdescribed herein, which are pharmaceutically active in vivo. Suchexamples include, but are not limited to, choline ester derivatives andthe like, N-alkylmorpholine esters and the like. Other derivatives ofthe compounds described herein have activity in both their acid and acidderivative forms, but in the acid sensitive form often offer advantagesof solubility, tissue compatibility, or delayed release in the mammalianorganism (see, Bundgard, H., Design of Prodrugs, pp. 7-9, 21-24,Elsevier, Amsterdam 1985). Prodrugs include acid derivatives well knownto practitioners of the art, such as, for example, esters prepared byreaction of the parent acid with a suitable alcohol, or amides preparedby reaction of the parent acid compound with a substituted orunsubstituted amine, or acid anhydrides, or mixed anhydrides. Simplealiphatic or aromatic esters, amides, and anhydrides derived from acidicgroups pendant on the compounds described herein are particularprodrugs. In some cases it is desirable to prepare double ester typeprodrugs such as (acyloxy)alkyl esters or((alkoxycarbonyl)oxy)alkylesters. C₁-C₈ alkyl, C₂-C₈ alkenyl, C₂-C₈alkynyl, aryl, C₇-C₁₂ substituted aryl, and C₇-C₁₂ arylalkyl esters ofthe compounds described herein may be preferred.

The term “lipophilic” or “hydrophobic” refers to the ability of acompound to dissolve, or the ability of a moiety of a compound to assistthe compound in dissolving in fats, oils, lipids, and/or non-polarsolvents (e.g., hexane or toluene). Lipophilic moieties include, but arenot limited to, substituted or unsubstituted, branched or unbranchedalkyl groups having 1 to 50 carbon atoms. In certain embodiments, thelipophilic moiety is an alkyl group including at least 1, at least 6, atleast 12, at least 18, at least 24, at least 36, or at least 50 carbonatoms. In certain embodiments, the lipophilic moiety is an alkyl groupincluding at most 50, at most 36, at most 24, at most 18, at most 12, orat most 6 carbon atoms. Combinations of the above-referenced ranges(e.g., at least about 1 and at most about 24 carbon atoms) are alsowithin the scope of the disclosure. In certain embodiments, thelipophilic moiety is unsubstituted alkyl. In certain embodiments, thelipophilic moiety is unsubstituted and unbranched alkyl. In certainembodiments, the lipophilic moiety is unsubstituted and unbranched C₁₋₂₄alkyl. In certain embodiments, the lipophilic moiety is unsubstitutedand unbranched C₆₋₂₄ alkyl. In certain embodiments, the lipophilicmoiety is unsubstituted and unbranched C₁₂₋₂₄ alkyl.

The term “polymer” refers to a compound comprising eleven or morecovalently connected repeating units. In certain embodiments, a polymeris naturally occurring. In certain embodiments, a polymer is synthetic(i.e., not naturally occurring).

The “molecular weight” of a monovalent moiety —R is calculated bysubtracting 1 from the molecular weight of the compound R—H. The“molecular weight” of a divalent moiety -L- is calculated by subtracting2 from the molecular weight of the compound H-L-H.

The term “small molecule” refers to molecules, whethernaturally-occurring or artificially created (e.g., via chemicalsynthesis) that have a relatively low molecular weight. Typically, asmall molecule is an organic compound (i.e., it contains carbon). Thesmall molecule may contain multiple carbon-carbon bonds, stereocenters,and other functional groups (e.g., amines, hydroxyl, carbonyls, andheterocyclic rings, etc.). In certain embodiments, the molecular weightof a small molecule is at most about 1,000 g/mol, at most about 900g/mol, at most about 800 g/mol, at most about 700 g/mol, at most about600 g/mol, at most about 500 g/mol, at most about 400 g/mol, at mostabout 300 g/mol, at most about 200 g/mol, or at most about 100 g/mol. Incertain embodiments, the molecular weight of a small molecule is atleast about 100 g/mol, at least about 200 g/mol, at least about 300g/mol, at least about 400 g/mol, at least about 500 g/mol, at leastabout 600 g/mol, at least about 700 g/mol, at least about 800 g/mol, orat least about 900 g/mol, or at least about 1,000 g/mol. Combinations ofthe above ranges (e.g., at least about 200 g/mol and at most about 500g/mol) are also possible. In certain embodiments, the small molecule isa therapeutically active agent such as a drug (e.g., a molecule approvedby the U.S. Food and Drug Administration as provided in the Code ofFederal Regulations (C.F.R.)). The small molecule may also be complexedwith one or more metal atoms and/or metal ions. In this instance, thesmall molecule is also referred to as a “small organometallic molecule.”Preferred small molecules are biologically active in that they produce abiological effect in animals, preferably mammals, more preferablyhumans. Small molecules include, but are not limited to, radionuclidesand imaging agents. In certain embodiments, the small molecule is adrug. Preferably, though not necessarily, the drug is one that hasalready been deemed safe and effective for use in humans or animals bythe appropriate governmental agency or regulatory body. For example,drugs approved for human use are listed by the FDA under 21 C.F.R. § §330.5, 331 through 361, and 440 through 460, incorporated herein byreference; drugs for veterinary use are listed by the FDA under 21C.F.R. § § 500 through 589, incorporated herein by reference. All listeddrugs are considered acceptable for use in accordance with the presentdisclosure.

A “protein,” “peptide,” or “polypeptide” comprises a polymer of aminoacid residues linked together by peptide bonds. The term refers toproteins, polypeptides, and peptides of any size, structure, orfunction. Typically, a protein will be at least three amino acids long.A protein may refer to an individual protein or a collection ofproteins. The proteins preferably contain only natural amino acids,although non-natural amino acids (i.e., compounds that do not occur innature but that can be incorporated into a polypeptide chain) and/oramino acid analogs as are known in the art may alternatively beemployed. Also, one or more of the amino acids in a protein may bemodified, for example, by the addition of a chemical entity such as acarbohydrate group, a hydroxyl group, a phosphate group, a farnesylgroup, an isofamesyl group, a fatty acid group, a linker for conjugationor functionalization, or other modification. A protein may also be asingle molecule or may be a multi-molecular complex. A protein may be afragment of a naturally occurring protein or peptide. A protein may benaturally occurring, recombinant, synthetic, or any combination ofthese.

The term “gene” refers to a nucleic acid fragment that expresses aspecific protein, including regulatory sequences preceding (5′non-coding sequences) and following (3′ non-coding sequences) the codingsequence. “Native gene” refers to a gene as found in nature with its ownregulatory sequences. “Chimeric gene” or “chimeric construct” refers toany gene or a construct, not a native gene, comprising regulatory andcoding sequences that are not found together in nature. Accordingly, achimeric gene or chimeric construct may comprise regulatory sequencesand coding sequences that are derived from different sources, orregulatory sequences and coding sequences derived from the same source,but arranged in a manner different than that found in nature.“Endogenous gene” refers to a native gene in its natural location in thegenome of an organism. A “foreign” gene refers to a gene not normallyfound in the host organism, but which is introduced into the hostorganism by gene transfer. Foreign genes can comprise native genesinserted into a non-native organism, or chimeric genes. A “transgene” isa gene that has been introduced into the genome by a transformationprocedure.

The terms “polynucleotide”, “nucleotide sequence”, “nucleic acid”,“nucleic acid molecule”, “nucleic acid sequence”, and “oligonucleotide”refer to a series of nucleotide bases (also called “nucleotides”) in DNAand RNA, and mean any chain of two or more nucleotides. Thepolynucleotides can be chimeric mixtures or derivatives or modifiedversions thereof, single-stranded or double-stranded. Theoligonucleotide can be modified at the base moiety, sugar moiety, orphosphate backbone, for example, to improve stability of the molecule,its hybridization parameters, etc. The antisense oligonuculeotide maycomprise a modified base moiety which is selected from the groupincluding, but not limited to, 5-fluorouracil, 5-bromouracil,5-chlorouracil, 5-iodouracil, hypoxanthine, xanthine, 4-acetylcytosine,5-(carboxyhydroxylmethyl) uracil,5-carboxymethylaminomethyl-2-thiouridine,5-carboxymethylaminomethyluracil, dihydrouracil,beta-D-galactosylqueosine, inosine, N6-isopentenyladenine,1-methylguanine, 1-methylinosine, 2,2-dimethylguanine, 2-methyladenine,2-methylguanine, 3-methylcytosine, 5-methylcytosine, N6-adenine,7-methylguanine, 5-methylaminomethyluracil,5-methoxyaminomethyl-2-thiouracil, beta-D-mannosylqueosine,5′-methoxycarboxymethyluracil, 5-methoxyuracil,2-methylthio-N6-isopentenyladenine, wybutoxosine, pseudouracil,queosine, 2-thiocytosine, 5-methyl-2-thiouracil, 2-thiouracil,4-thiouracil, 5-methyluracil, uracil-5-oxyacetic acid methylester,uracil-5-oxyacetic acid, 5-methyl-2-thiouracil,3-(3-amino-3-N-2-carboxypropyl) uracil, a thio-guanine, and2,6-diaminopurine. A nucleotide sequence typically carries geneticinformation, including the information used by cellular machinery tomake proteins and enzymes. These terms include double- orsingle-stranded genomic and cDNA, RNA, any synthetic and geneticallymanipulated polynucleotide, and both sense and antisensepolynucleotides. This includes single- and double-stranded molecules,i.e., DNA-DNA, DNA-RNA and RNA-RNA hybrids, as well as “protein nucleicacids” (PNAs) formed by conjugating bases to an amino acid backbone.This also includes nucleic acids containing carbohydrate or lipids.Exemplary DNAs include single-stranded DNA (ssDNA), double-stranded DNA(dsDNA), plasmid DNA (pDNA), genomic DNA (gDNA), complementary DNA(cDNA), antisense DNA, chloroplast DNA (ctDNA or cpDNA), microsatelliteDNA, mitochondrial DNA (mtDNA or mDNA), kinetoplast DNA (kDNA),provirus, lysogen, repetitive DNA, satellite DNA, and viral DNA.Exemplary RNAs include single-stranded RNA (ssRNA), double-stranded RNA(dsRNA), small interfering RNA (siRNA), messenger RNA (mRNA), precursormessenger RNA (pre-mRNA), small hairpin RNA or short hairpin RNA(shRNA), microRNA (miRNA), guide RNA (gRNA), transfer RNA (tRNA),antisense RNA (asRNA), heterogeneous nuclear RNA (hnRNA), coding RNA,non-coding RNA (ncRNA), long non-coding RNA (long ncRNA or IncRNA),satellite RNA, viral satellite RNA, signal recognition particle RNA,small cytoplasmic RNA, small nuclear RNA (snRNA), ribosomal RNA (rRNA),Piwi-interacting RNA (piRNA), polyinosinic acid, ribozyme, flexizyme,small nucleolar RNA (snoRNA), spliced leader RNA, viral RNA, and viralsatellite RNA.

Polynucleotides described herein may be synthesized by standard methodsknown in the art, e.g., by use of an automated DNA synthesizer (such asthose that are commercially available from Biosearch, AppliedBiosystems, etc.). As examples, phosphorothioate oligonucleotides may besynthesized by the method of Stein et al., Nucl. Acids Res., 16, 3209,(1988), methylphosphonate oligonucleotides can be prepared by use ofcontrolled pore glass polymer supports (Sarin et al., Proc. Natl. Acad.Sci. U.S.A. 85, 7448-7451, (1988)). A number of methods have beendeveloped for delivering antisense DNA or RNA to cells, e.g., antisensemolecules can be injected directly into the tissue site, or modifiedantisense molecules, designed to target the desired cells (antisenselinked to peptides or antibodies that specifically bind receptors orantigens expressed on the target cell surface) can be administeredsystemically. Alternatively, RNA molecules may be generated by in vitroand in vivo transcription of DNA sequences encoding the antisense RNAmolecule. Such DNA sequences may be incorporated into a wide variety ofvectors that incorporate suitable RNA polymerase promoters such as theT7 or SP6 polymerase promoters. Alternatively, antisense cDNA constructsthat synthesize antisense RNA constitutively or inducibly, depending onthe promoter used, can be introduced stably into cell lines. However, itis often difficult to achieve intracellular concentrations of theantisense sufficient to suppress translation of endogenous mRNAs.Therefore a preferred approach utilizes a recombinant DNA construct inwhich the antisense oligonucleotide is placed under the control of astrong promoter. The use of such a construct to transfect target cellsin the subject will result in the transcription of sufficient amounts ofsingle stranded RNAs that will form complementary base pairs with theendogenous target gene transcripts and thereby prevent translation ofthe target gene mRNA. For example, a vector can be introduced in vivosuch that it is taken up by a cell and directs the transcription of anantisense RNA. Such a vector can remain episomal or become chromosomallyintegrated, as long as it can be transcribed to produce the desiredantisense RNA. Such vectors can be constructed by recombinant DNAtechnology methods standard in the art. Vectors can be plasmid, viral,or others known in the art, used for replication and expression inmammalian cells. Expression of the sequence encoding the antisense RNAcan be by any promoter known in the art to act in mammalian, preferablyhuman, cells. Such promoters can be inducible or constitutive. Suchpromoters include, but are not limited to: the SV40 early promoterregion (Bemoist et al., Nature, 290, 304-310, (1981); Yamamoto et al.,Cell, 22, 787-797, (1980); Wagner et al., Proc. Natl. Acad. Sci. U.S.A.78, 1441-1445, (1981); Brinster et al., Nature 296, 39-42, (1982)). Anytype of plasmid, cosmid, yeast artificial chromosome, or viral vectorcan be used to prepare the recombinant DNA construct that can beintroduced directly into the tissue site. Alternatively, viral vectorscan be used which selectively infect the desired tissue, in which caseadministration may be accomplished by another route (e.g.,systemically).

The polynucleotides may be flanked by natural regulatory (expressioncontrol) sequences or may be associated with heterologous sequences,including promoters, internal ribosome entry sites (IRES) and otherribosome binding site sequences, enhancers, response elements,suppressors, signal sequences, polyadenylation sequences, introns, 5′-and 3′-non-coding regions, and the like. The nucleic acids may also bemodified by many means known in the art. Non-limiting examples of suchmodifications include methylation, “caps”, substitution of one or moreof the naturally occurring nucleotides with an analog, andinternucleotide modifications, such as, for example, those withuncharged linkages (e.g., methyl phosphonates, phosphotriesters,phosphoroamidates, carbamates, etc.) and with charged linkages (e.g.,phosphorothioates, phosphorodithioates, etc.). Polynucleotides maycontain one or more additional covalently linked moieties, such as, forexample, proteins (e.g., nucleases, toxins, antibodies, signal peptides,poly-L-lysine, etc.), intercalators (e.g., acridine, psoralen, etc.),chelators (e.g., metals, radioactive metals, iron, oxidative metals,etc.), and alkylators. The polynucleotides may be derivatized byformation of a methyl or ethyl phosphotriester or an alkylphosphoramidate linkage. Furthermore, the polynucleotides herein mayalso be modified with a label capable of providing a detectable signal,either directly or indirectly. Exemplary labels include radioisotopes,fluorescent molecules, isotopes (e.g., radioactive isotopes), biotin,and the like.

A “recombinant nucleic acid molecule” is a nucleic acid molecule thathas undergone a molecular biological manipulation, i.e., non-naturallyoccurring nucleic acid molecule or genetically engineered nucleic acidmolecule. Furthermore, the term “recombinant DNA molecule” refers to anucleic acid sequence which is not naturally occurring, or can be madeby the artificial combination of two otherwise separated segments ofnucleic acid sequence, i.e., by ligating together pieces of DNA that arenot normally continuous. By “recombinantly produced” is meant artificialcombination often accomplished by either chemical synthesis means, or bythe artificial manipulation of isolated segments of nucleic acids, e.g.,by genetic engineering techniques using restriction enzymes, ligases,and similar recombinant techniques as described by, for example,Sambrook et al., Molecular Cloning, second edition, Cold Spring HarborLaboratory, Plainview, N.Y.; (1989), or Ausubel et al., CurrentProtocols in Molecular Biology, Current Protocols (1989), and DNACloning: A Practical Approach, Volumes I and II (ed. D. N. Glover) IRELPress, Oxford, (1985); each of which is incorporated herein byreference.

Such manipulation may be done to replace a codon with a redundant codonencoding the same or a conservative amino acid, while typicallyintroducing or removing a sequence recognition site. Alternatively, itmay be performed to join together nucleic acid segments of desiredfunctions to generate a single genetic entity comprising a desiredcombination of functions not found in nature. Restriction enzymerecognition sites are often the target of such artificial manipulations,but other site specific targets, e.g., promoters, DNA replication sites,regulation sequences, control sequences, open reading frames, or otheruseful features may be incorporated by design.

The term “pDNA,” “plasmid DNA,” or “plasmid” refers to a small DNAmolecule that is physically separate from, and can replicateindependently of, chromosomal DNA within a cell. Plasmids can be foundin all three major domains: Archaea, Bacteria, and Eukarya. In nature,plasmids carry genes that may benefit survival of the subject (e.g.,antibiotic resistance) and can frequently be transmitted from onebacterium to another (even of another species) via horizontal genetransfer. Artificial plasmids are widely used as vectors in molecularcloning, serving to drive the replication of recombinant DNA sequenceswithin host subjects. Plasmid sizes may vary from 1 to over 1,000 kbp.Plasmids are considered replicons, capable of replicating autonomouslywithin a suitable host.

“RNA transcript” refers to the product resulting from RNApolymerase-catalyzed transcription of a DNA sequence. When the RNAtranscript is a complementary copy of the DNA sequence, it is referredto as the primary transcript, or it may be an RNA sequence derived frompost-transcriptional processing of the primary transcript and isreferred to as the mature RNA. “Messenger RNA (mRNA)” refers to the RNAthat is without introns and can be translated into polypeptides by thecell. “cRNA” refers to complementary RNA, transcribed from a recombinantcDNA template. “cDNA” refers to DNA that is complementary to and derivedfrom an mRNA template. The cDNA can be single-stranded or converted todouble-stranded form using, for example, the Klenow fragment of DNApolymerase I.

A sequence “complementary” to a portion of an RNA, refers to a sequencehaving sufficient complementarity to be able to hybridize with the RNA,forming a stable duplex; in the case of double-stranded antisensenucleic acids, a single strand of the duplex DNA may thus be tested, ortriplex formation may be assayed. The ability to hybridize will dependon both the degree of complementarity and the length of the antisensenucleic acid. Generally, the longer the hybridizing nucleic acid, themore base mismatches with an RNA it may contain and still form a stableduplex (or triplex, as the case may be). One skilled in the art canascertain a tolerable degree of mismatch by use of standard proceduresto determine the melting point of the hybridized complex.

The terms “nucleic acid” or “nucleic acid sequence”, “nucleic acidmolecule”, “nucleic acid fragment” or “polynucleotide” may be usedinterchangeably with “gene”, “mRNA encoded by a gene” and “cDNA”.

The term “mRNA” or “mRNA molecule” refers to messenger RNA, or the RNAthat serves as a template for protein synthesis in a cell. The sequenceof a strand of mRNA is based on the sequence of a complementary strandof DNA comprising a sequence coding for the protein to be synthesized.

The term “siRNA” or “siRNA molecule” refers to small inhibitory RNAduplexes that induce the RNA interference (RNAi) pathway, where thesiRNA interferes with the expression of specific genes with acomplementary nucleotide sequence. siRNA molecules can vary in length(e.g., between 18-30 or 20-25 basepairs) and contain varying degrees ofcomplementarity to their target mRNA in the antisense strand. Some siRNAhave unpaired overhanging bases on the 5′ or 3′ end of the sense strandand/or the antisense strand. The term siRNA includes duplexes of twoseparate strands, as well as single strands that can form hairpinstructures comprising a duplex region.

The term “gene silencing” refers to an epigenetic process of generegulation where a gene is “switched off” by a mechanism other thangenetic modification. That is, a gene which would be expressed (i.e.,“turned on”) under normal circumstances is switched off by machinery inthe cell. Gene silencing occurs when RNA is unable to make a proteinduring translation. Genes are regulated at either the transcriptional orpost-transcriptional level. Transcriptional gene silencing is the resultof histone modifications, creating an environment of heterochromatinaround a gene that makes it inaccessible to transcriptional machinery(e.g., RNA polymerase and transcription factors). Post-transcriptionalgene silencing is the result of mRNA of a particular gene beingdestroyed or blocked. The destruction of the mRNA prevents translationand thus the formation of a gene product (e.g., a protein). A commonmechanism of post-transcriptional gene silencing is RNAi.

The term “sphere” or “spherical” refers to a cage-like structure, whichis hollow and has at least one reflectional symmetry, rotationalsymmetry, or a combination thereof. The term “nanosphere” refers to asphere, wherein the maximum diameter of the sphere is between 1nanometer (nm) and about 1 micrometer (μm) (e.g., between about 1 nm andabout 300 nm, between about 1 nm and about 100 nm, between about 1 nmand about 30 nm, between about 1 nm and about 10 nm, or between about 1nm and about 3 nm), inclusive).

The term “paddlewheel” refers to a coordination complex comprising minstances of ligands and two metal centers (metal atoms or metal ions),wherein there is an axis of symmetry connecting the two metal centers,and the overall symmetry of the coordination complex falls into the Dmhpoint group. In certain embodiments, m is 4, and the point group is D4h(e.g., there is a four-fold axis of symmetry when looking down the metalcenters). In certain embodiments, the geometry of each of the metalcenters is substantially square planar. In certain embodiments, m is 3.The term “nano-paddlewheel” refers to a paddlewheel, wherein the maximumdiameter of the paddlewheel is between 1 nanometer (nm) and about 1micrometer (μm) (e.g., between about 1 nm and about 300 nm, betweenabout 1 nm and about 100 nm, between about 1 nm and about 30 nm, betweenabout 1 nm and about 10 nm, or between about 1 nm and about 3 nm),inclusive). In certain embodiments, a nano-paddlewheel described hereinis of the formula depicted in Scheme 8.

The term “particle” refers to a small object, fragment, or piece of asubstance that may be a single element, inorganic material, organicmaterial, or mixture thereof. Examples of particles include polymericparticles, single-emulsion particles, double-emulsion particles,coacervates, liposomes, microparticles, nanoparticles, macroscopicparticles, pellets, crystals, aggregates, composites, pulverized, milledor otherwise disrupted matrices, and cross-linked protein orpolysaccharide particles, each of which have an average (e.g., mean)characteristic dimension of about not more than about 1 mm and at least1 nm, where the characteristic dimension, or “critical dimension,” ofthe particle is the smallest cross-sectional dimension of the particle.A particle may be composed of a single substance or multiple substances.In certain embodiments, the particle is not a viral particle. In otherembodiments, the particle is not a liposome. In certain embodiments, theparticle is not a micelle. In certain embodiments, the particle issubstantially solid throughout. In certain embodiments, the particle isa nanoparticle. In certain embodiments, the particle is a microparticle.

The term “nanoparticle” refers to a particle having an average (e.g.,mean) dimension (e.g., diameter) of between about 1 nanometer (nm) andabout 1 micrometer (μm) (e.g., between about 1 nm and about 300 nm,between about 1 nm and about 100 nm, between about 1 nm and about 30 nm,between about 1 nm and about 10 nm, or between about 1 nm and about 3nm), inclusive.

The term “microparticle” refers to a particle having an average (e.g.,mean) dimension (e.g., diameter) of between about 1 micrometer (μm) andabout 1 millimeter (mm) (e.g., between about 1 μm and about 100 μm,between about 1 μm and about 30 μm, between about 1 μm and about 10 μm,or between about 1 μm and about 3 μm), inclusive.

The term “fluid” refers to a substance that, under a shear stress at 25°C., continually flows (e.g., at a velocity of 1 millimeter per second)along a solid boundary. Examples of fluids include liquids (e.g.,solvents and solutions), gases, and suspensions (where solids aresuspended in a liquid or gas). In certain embodiments, a fluid is water.In certain embodiments, a fluid is DMSO or acetonitrile. In certainembodiments, a fluid is water, DMSO, acetonide, or a mixture thereof. A“nonfluid” is a substance that is not a fluid.

The term “gel” is a nonfluid colloidal network or nonfluid polymernetwork that is expanded throughout its whole volume by a fluid (e.g., asolvent (e.g., water) or a solution (e.g., an aqueous solution)). A gelhas a finite, usually rather small, yield stress. A gel may contain: (i)a covalent molecular network (e.g., polymer network), e.g., a networkformed by crosslinking molecules (e.g., polymers) or by nonlinearpolymerization; (ii) a molecular network (e.g., polymer network) formedthrough non-covalent aggregation of molecules (e.g., polymers), causedby complexation (e.g., coordination bond formation between a ligand anda metal, the resulting gel referring to a “metallogel”), electrostaticinteractions, hydrophobic interactions, hydrogen bonding, van der Waalsinteractions, π-π stacking, or a combination thereof, that results inregions of local order acting as the network junction points. The term“thermoreversible gel” refers to a gel where the regions of local orderin the gel are thermally reversible; (iii) a polymer network formedthrough glassy junction points, e.g., one based on block copolymers. Ifthe junction points are thermally reversible glassy domains, theresulting swollen network may also be termed a thermoreversible gel;(iv) lamellar structures including mesophases, e.g., soap gels,phospholipids, and clays; or (v) particulate disordered structures,e.g., a flocculent precipitate usually consisting of particles withlarge geometrical anisotropy, such as in V₂O₅ gels and globular orfibrillar protein gels. The term “hydrogel” refers to a gel, in whichthe fluid is water.

The term “interstructural” refers to a divalent linker Y directlycovalently attached to two different instances of a nanostructure.

The term “intrastructural” refers to a divalent linker Y directlycovalently attached to the same instance of a nanostructure.

The terms “composition” and “formulation” are used interchangeably.

The term “toxic” refers to a substance showing detrimental, deleterious,harmful, or otherwise negative effects on a subject, tissue, or cellwhen or after administering the substance to the subject or contactingthe tissue or cell with the substance, compared to the subject, tissue,or cell prior to administering the substance to the subject orcontacting the tissue or cell with the substance. In certainembodiments, the effect is death or destruction of the subject, tissue,or cell. In certain embodiments, the effect is a detrimental effect onthe metabolism of the subject, tissue, or cell. In certain embodiments,a toxic substance is a substance that has a median lethal dose (LD₅₀) ofnot more than 500 milligrams per kilogram of body weight whenadministered orally to an albino rat weighing between 200 and 300 grams,inclusive. In certain embodiments, a toxic substance is a substance thathas an LD₅₀ of not more than 1,000 milligrams per kilogram of bodyweight when administered by continuous contact for 24 hours (or less ifdeath occurs within 24 hours) with the bare skin of an albino rabbitweighing between two and three kilograms, inclusive. In certainembodiments, a toxic substance is a substance that has an LCso in air ofnot more than 2,000 parts per million by volume of gas or vapor, or notmore than 20 milligrams per liter of mist, fume, or dust, whenadministered by continuous inhalation for one hour (or less if deathoccurs within one hour) to an albino rat weighing between 200 and 300grams, inclusive. The term “non-toxic” refers to a substance that is nottoxic.

A “subject” to which administration is contemplated refers to a human(i.e., male or female of any age group, e.g., pediatric subject (e.g.,infant, child, or adolescent) or adult subject (e.g., young adult,middle-aged adult, or senior adult)) or non-human animal. In certainembodiments, the non-human animal is a mammal (e.g., primate (e.g.,cynomolgus monkey or rhesus monkey), commercially relevant mammal (e.g.,cattle, pig, horse, sheep, goat, cat, or dog), or bird (e.g.,commercially relevant bird, such as chicken, duck, goose, or turkey)).In certain embodiments, the non-human animal is a fish, reptile, oramphibian. The non-human animal may be a male or female at any stage ofdevelopment. The non-human animal may be a transgenic animal orgenetically engineered animal.

The term “target tissue” refers to any biological tissue of a subject(including a group of cells, a body part, or an organ) or a partthereof, including blood and/or lymph vessels, which is the object towhich a compound, particle, and/or composition of the disclosure isdelivered. A target tissue may be an abnormal or unhealthy tissue, whichmay need to be treated. A target tissue may also be a normal or healthytissue that is under a higher than normal risk of becoming abnormal orunhealthy, which may need to be prevented. In certain embodiments, thetarget tissue is the liver. In certain embodiments, the target tissue isthe lung. In certain embodiments, the target tissue is the spleen. A“non-target tissue” is any biological tissue of a subject (including agroup of cells, a body part, or an organ) or a part thereof, includingblood and/or lymph vessels, which is not a target tissue.

The terms “administer,” “administering,” or “administration” refers toimplanting, absorbing, ingesting, injecting, inhaling, or otherwiseintroducing a compound described herein, or a composition thereof, in oron a subject.

The terms “treatment,” “treat,” and “treating” refer to reversing,alleviating, delaying the onset of, or inhibiting the progress of adisease described herein. In some embodiments, treatment may beadministered after one or more signs or symptoms of the disease havedeveloped or have been observed. In other embodiments, treatment may beadministered in the absence of signs or symptoms of the disease. Forexample, treatment may be administered to a susceptible subject prior tothe onset of symptoms (e.g., in light of a history of symptoms and/or inlight of exposure to a pathogen). Treatment may also be continued aftersymptoms have resolved, for example, to delay or prevent recurrence.

The terms “condition,” “disease,” and “disorder” are usedinterchangeably.

An “effective amount” of a compound described herein refers to an amountsufficient to elicit the desired biological response, i.e., treating thecondition. As will be appreciated by those of ordinary skill in thisart, the effective amount of a compound described herein may varydepending on such factors as the desired biological endpoint, thepharmacokinetics of the compound, the condition being treated, the modeof administration, and the age and health of the subject. An effectiveamount encompasses therapeutic and prophylactic treatment.

A “therapeutically effective amount” of a compound described herein isan amount sufficient to provide a therapeutic benefit in the treatmentof a condition or to delay or minimize one or more symptoms associatedwith the condition. A therapeutically effective amount of a compoundmeans an amount of therapeutic agent, alone or in combination with othertherapies, which provides a therapeutic benefit in the treatment of thecondition. The term “therapeutically effective amount” can encompass anamount that improves overall therapy, reduces or avoids symptoms, signs,or causes of the condition, and/or enhances the therapeutic efficacy ofanother therapeutic agent.

A “prophylactically effective amount” of a compound described herein isan amount sufficient to prevent a condition, or one or more symptomsassociated with the condition or prevent its recurrence. Aprophylactically effective amount of a compound means an amount of atherapeutic agent, alone or in combination with other agents, whichprovides a prophylactic benefit in the prevention of the condition. Theterm “prophylactically effective amount” can encompass an amount thatimproves overall prophylaxis or enhances the prophylactic efficacy ofanother prophylactic agent.

The term “genetic disease” refers to a disease caused by one or moreabnormalities in the genome of a subject, such as a disease that ispresent from birth of the subject. Genetic diseases may be heritable andmay be passed down from the parents' genes. A genetic disease may alsobe caused by mutations or changes of the DNAs and/or RNAs of thesubject. In such cases, the genetic disease will be heritable if itoccurs in the germline. Exemplary genetic diseases include, but are notlimited to, Aarskog-Scott syndrome, Aase syndrome, achondroplasia,acrodysostosis, addiction, adreno-leukodystrophy, albinism,ablepharon-macrostomia syndrome, alagille syndrome, alkaptonuria,alpha-1 antitrypsin deficiency, Alport's syndrome, Alzheimer's disease,asthma, autoimmune polyglandular syndrome, androgen insensitivitysyndrome, Angelman syndrome, ataxia, ataxia telangiectasia,atherosclerosis, attention deficit hyperactivity disorder (ADHD),autism, baldness, Batten disease, Beckwith-Wiedemann syndrome, Bestdisease, bipolar disorder, brachydactyl), breast cancer, Burkittlymphoma, chronic myeloid leukemia, Charcot-Marie-Tooth disease, Crohn'sdisease, cleft lip, Cockayne syndrome, Coffin Lowry syndrome, coloncancer, congenital adrenal hyperplasia, Cornelia de Lange syndrome,Costello syndrome, Cowden syndrome, craniofrontonasal dysplasia,Crigler-Najjar syndrome, Creutzfeldt-Jakob disease, cystic fibrosis,deafness, depression, diabetes, diastrophic dysplasia, DiGeorgesyndrome, Down's syndrome, dyslexia, Duchenne muscular dystrophy,Dubowitz syndrome, ectodermal dysplasia Ellis-van Creveld syndrome,Ehlers-Danlos, epidermolysis bullosa, epilepsy, essential tremor,familial hypercholesterolemia, familial Mediterranean fever, fragile Xsyndrome, Friedreich's ataxia, Gaucher disease, glaucoma, glucosegalactose malabsorption, glutaricaciduria, gyrate atrophy, GoldbergShprintzen syndrome (velocardiofacial syndrome), Gorlin syndrome,Hailey-Hailey disease, hemihypertrophy, hemochromatosis, hemophilia,hereditary motor and sensory neuropathy (HMSN), hereditary non polyposiscolorectal cancer (HNPCC), Huntington's disease, immunodeficiency withhyper-IgM, juvenile onset diabetes, Klinefelter's syndrome, Kabukisyndrome, Leigh's disease, long QT syndrome, lung cancer, malignantmelanoma, manic depression, Marfan syndrome, Menkes syndrome,miscarriage, mucopolysaccharide disease, multiple endocrine neoplasia,multiple sclerosis, muscular dystrophy, myotrophic lateral sclerosis,myotonic dystrophy, neurofibromatosis, Niemann-Pick disease, Noonansyndrome, obesity, ovarian cancer, pancreatic cancer, Parkinson'sdisease, paroxysmal nocturnal hemoglobinuria, Pendred syndrome, peronealmuscular atrophy, phenylketonuria (PKU), polycystic kidney disease,Prader-Willi syndrome, primary biliary cirrhosis, prostate cancer, REARsyndrome, Refsum disease, retinitis pigmentosa, retinoblastoma, Rettsyndrome, Sanfilippo syndrome, schizophrenia, severe combinedimmunodeficiency, sickle cell anemia, spina bifida, spinal muscularatrophy, spinocerebellar atrophy, sudden adult death syndrome, Tangierdisease, Tay-Sachs disease, thrombocytopenia absent radius syndrome,Townes-Brocks syndrome, tuberous sclerosis, Turner syndrome, Ushersyndrome, von Hippel-Lindau syndrome, Waardenburg syndrome, Weaversyndrome, Werner syndrome, Williams syndrome, Wilson's disease,xeroderma piginentosum, and Zellweger syndrome.

A “proliferative disease” refers to a disease that occurs due toabnormal growth or extension by the multiplication of cells (Walker,Cambridge Dictionary of Biology; Cambridge University Press: Cambridge,UK, 1990). A proliferative disease may be associated with: 1) thepathological proliferation of normally quiescent cells; 2) thepathological migration of cells from their normal location (e.g.,metastasis of neoplastic cells); 3) the pathological expression ofproteolytic enzymes such as the matrix metalloproteinases (e.g.,collagenases, gelatinases, and elastases); or 4) the pathologicalangiogenesis as in proliferative retinopathy and tumor metastasis.Exemplary proliferative diseases include cancers (i.e., “malignantneoplasms”), benign neoplasms, angiogenesis, inflammatory diseases, andautoimmune diseases.

The term “angiogenesis” refers to the physiological process throughwhich new blood vessels form from pre-existing vessels. Angiogenesis isdistinct from vasculogenesis, which is the de novo formation ofendothelial cells from mesoderm cell precursors. The first vessels in adeveloping embryo form through vasculogenesis, after which angiogenesisis responsible for most blood vessel growth during normal or abnormaldevelopment. Angiogenesis is a vital process in growth and development,as well as in wound healing and in the formation of granulation tissue.However, angiogenesis is also a fundamental step in the transition oftumors from a benign state to a malignant one, leading to the use ofangiogenesis inhibitors in the treatment of cancer. Angiogenesis may bechemically stimulated by angiogenic proteins, such as growth factors(e.g., VEGF). “Pathological angiogenesis” refers to abnormal (e.g.,excessive or insufficient) angiogenesis that amounts to and/or isassociated with a disease.

The terms “neoplasm” and “tumor” are used interchangeably and refer toan abnormal mass of tissue wherein the growth of the mass surpasses andis not coordinated with the growth of a normal tissue. A neoplasm ortumor may be “benign” or “malignant,” depending on the followingcharacteristics: degree of cellular differentiation (includingmorphology and functionality), rate of growth, local invasion, andmetastasis. A “benign neoplasm” is generally well differentiated, hascharacteristically slower growth than a malignant neoplasm, and remainslocalized to the site of origin. In addition, a benign neoplasm does nothave the capacity to infiltrate, invade, or metastasize to distantsites. Exemplary benign neoplasms include, but are not limited to,lipoma, chondroma, adenomas, acrochordon, senile angiomas, seborrheickeratoses, lentigos, and sebaceous hyperplasias. In some cases, certain“benign” tumors may later give rise to malignant neoplasms, which mayresult from additional genetic changes in a subpopulation of the tumor'sneoplastic cells, and these tumors are referred to as “pre-malignantneoplasms.” An exemplary pre-malignant neoplasm is a teratoma. Incontrast, a “malignant neoplasm” is generally poorly differentiated(anaplasia) and has characteristically rapid growth accompanied byprogressive infiltration, invasion, and destruction of the surroundingtissue. Furthermore, a malignant neoplasm generally has the capacity tometastasize to distant sites. The term “metastasis,” “metastatic,” or“metastasize” refers to the spread or migration of cancerous cells froma primary or original tumor to another organ or tissue and is typicallyidentifiable by the presence of a “secondary tumor” or “secondary cellmass” of the tissue type of the primary or original tumor and not ofthat of the organ or tissue in which the secondary (metastatic) tumor islocated. For example, a prostate cancer that has migrated to bone issaid to be metastasized prostate cancer and includes cancerous prostatecancer cells growing in bone tissue.

The term “cancer” refers to a malignant neoplasm (Stedman's MedicalDictionary, 25th ed.; Hensyl ed.; Williams & Wilkins: Philadelphia,1990). Exemplary cancers include, but are not limited to, acousticneuroma; adenocarcinoma; adrenal gland cancer, anal cancer, angiosarcoma(e.g., lymphangiosarcoma, lymphangioendotheliosarcoma, hemangiosarcoma);appendix cancer; benign monoclonal gammopathy; biliary cancer (e.g.,cholangiocarcinoma); bladder cancer, breast cancer (e.g., adenocarcinomaof the breast, papillary carcinoma of the breast, mammary cancer,medullary carcinoma of the breast); brain cancer (e.g., meningioma,glioblastomas, glioma (e.g., astrocytoma, oligodendroglioma),medulloblastoma); bronchus cancer; carcinoid tumor; cervical cancer(e.g., cervical adenocarcinoma); choriocarcinoma; chordoma;craniopharyngioma; colorectal cancer (e.g., colon cancer, rectal cancer,colorectal adenocarcinoma); connective tissue cancer, epithelialcarcinoma; ependymoma; endotheliosarcoma (e.g., Kaposi's sarcoma,multiple idiopathic hemorrhagic sarcoma); endometrial cancer (e.g.,uterine cancer, uterine sarcoma); esophageal cancer (e.g.,adenocarcinoma of the esophagus, Barrett's adenocarcinoma); Ewing'ssarcoma; ocular cancer (e.g., intraocular melanoma, retinoblastoma);familiar hypereosinophilia; gall bladder cancer, gastric cancer (e.g.,stomach adenocarcinoma); gastrointestinal stromal tumor (GIST); germcell cancer; head and neck cancer (e.g., head and neck squamous cellcarcinoma, oral cancer (e.g., oral squamous cell carcinoma), throatcancer (e.g., laryngeal cancer, pharyngeal cancer, nasopharyngealcancer, oropharyngeal cancer)); hematopoietic cancers (e.g., leukemiasuch as acute lymphocytic leukemia (ALL) (e.g., B-cell ALL, T-cell ALL),acute myelocytic leukemia (AML) (e.g., B-cell AML, T-cell AML), chronicmyelocytic leukemia (CML) (e.g., B-cell CML, T-cell CML), and chroniclymphocytic leukemia (CLL) (e.g., B-cell CLL, T-cell CLL)); lymphomasuch as Hodgkin lymphoma (HL) (e.g., B-cell HL, T-cell HL) andnon-Hodgkin lymphoma (NHL) (e.g., B-cell NHL such as diffuse large celllymphoma (DLCL) (e.g., diffuse large B-cell lymphoma), follicularlymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma(CLL/SLL), mantle cell lymphoma (MCL), marginal zone B-cell lymphomas(e.g., mucosa-associated lymphoid tissue (MALT) lymphomas, nodalmarginal zone B-cell lymphoma, splenic marginal zone B-cell lymphoma),primary mediastinal B-cell lymphoma, Burkitt lymphoma, lymphoplasmacyticlymphoma (i.e., Waldenstrim's macroglobulinemia), hairy cell leukemia(HCL), immunoblastic large cell lymphoma, precursor B-lymphoblasticlymphoma and primary central nervous system (CNS) lymphoma; and T-cellNHL such as precursor T-lymphoblastic lymphoma/leukemia, peripheralT-cell lymphoma (PTCL) (e.g., cutaneous T-cell lymphoma (CTCL) (e.g.,mycosis fungiodes, Sezary syndrome), angioimmunoblastic T-cell lymphoma,extranodal natural killer T-cell lymphoma, enteropathy type T-celllymphoma, subcutaneous panniculitis-like T-cell lymphoma, and anaplasticlarge cell lymphoma); a mixture of one or more leukemia/lymphoma asdescribed above; and multiple myeloma (MM)), heavy chain disease (e.g.,alpha chain disease, gamma chain disease, mu chain disease);hemangioblastoma; hypopharynx cancer; inflammatory myofibroblastictumors; immunocytic amyloidosis; kidney cancer (e.g., nephroblastomaa.k.a. Wilms' tumor, renal cell carcinoma); liver cancer (e.g.,hepatocellular cancer (HCC), malignant hepatoma); lung cancer (e.g.,bronchogenic carcinoma, small cell lung cancer (SCLC), non-small celllung cancer (NSCLC), adenocarcinoma of the lung); leiomyosarcoma (LMS);mastocytosis (e.g., systemic mastocytosis); muscle cancer;myelodysplastic syndrome (MDS); mesothelioma; myeloproliferativedisorder (MPD) (e.g., polycythemia vera (PV), essential thrombocytosis(ET), agnogenic myeloid metaplasia (AMM) a.k.a. myelofibrosis (MF),chronic idiopathic myelofibrosis, chronic myelocytic leukemia (CML),chronic neutrophilic leukemia (CNL), hypereosinophilic syndrome (HES));neuroblastoma; neurofibroma (e.g., neurofibromatosis (NF) type 1 or type2, schwannomatosis); neuroendocrine cancer (e.g., gastroenteropancreaticneuroendocrinetumor (GEP-NET), carcinoid tumor); osteosarcoma (e.g.,bone cancer); ovarian cancer (e.g., cystadenocarcinoma, ovarianembryonal carcinoma, ovarian adenocarcinoma); papillary adenocarcinoma;pancreatic cancer (e.g., pancreatic andenocarcinoma, intraductalpapillary mucinous neoplasm (IPMN), Islet cell tumors); penile cancer(e.g., Paget's disease of the penis and scrotum); pinealoma; primitiveneuroectodermal tumor (PNT); plasma cell neoplasia; paraneoplasticsyndromes; intraepithelial neoplasms; prostate cancer (e.g., prostateadenocarcinoma); rectal cancer, rhabdomyosarcoma; salivary gland cancer,skin cancer (e.g., squamous cell carcinoma (SCC), keratoacanthoma (KA),melanoma, basal cell carcinoma (BCC)); small bowel cancer (e.g.,appendix cancer); soft tissue sarcoma (e.g., malignant fibroushistiocytoma (MFH), liposarcoma, malignant peripheral nerve sheath tumor(MPNST), chondrosarcoma, fibrosarcoma, myxosarcoma); sebaceous glandcarcinoma; small intestine cancer, sweat gland carcinoma; synovioma;testicular cancer (e.g., seminoma, testicular embryonal carcinoma);thyroid cancer (e.g., papillary carcinoma of the thyroid, papillarythyroid carcinoma (PTC), medullary thyroid cancer); urethral cancer;vaginal cancer, and vulvar cancer (e.g., Paget's disease of the vulva).

The term “inflammatory disease” refers to a disease caused by, resultingfrom, or resulting in inflammation. The term “inflammatory disease” mayalso refer to a dysregulated inflammatory reaction that causes anexaggerated response by macrophages, granulocytes, and/or T-lymphocytesleading to abnormal tissue damage and/or cell death. An inflammatorydisease can be either an acute or chronic inflammatory condition and canresult from infections or non-infectious causes. Inflammatory diseasesinclude, without limitation, atherosclerosis, arteriosclerosis,autoimmune disorders, multiple sclerosis, systemic lupus erythematosus,polymyalgia rheumatica (PMR), gouty arthritis, degenerative arthritis,tendonitis, bursitis, psoriasis, cystic fibrosis, arthrosteitis,rheumatoid arthritis, inflammatory arthritis, Sjogren's syndrome, giantcell arteritis, progressive systemic sclerosis (scleroderma), ankylosingspondylitis, polymyositis, dermatomyositis, pemphigus, pemphigoid,diabetes (e.g., Type I), myasthenia gravis, Hashimoto's thyroiditis,Graves' disease, Goodpasture's disease, mixed connective tissue disease,sclerosing cholangitis, inflammatory bowel disease, Crohn's disease,ulcerative colitis, pernicious anemia, inflammatory dermatoses, usualinterstitial pneumonitis (UIP), asbestosis, silicosis, bronchiectasis,berylliosis, talcosis, pneumoconiosis, sarcoidosis, desquamativeinterstitial pneumonia, lymphoid interstitial pneumonia, giant cellinterstitial pneumonia, cellular interstitial pneumonia, extrinsicallergic alveolitis, Wegener's granulomatosis and related forms ofangiitis (temporal arteritis and polyarteritis nodosa), inflammatorydermatoses, hepatitis, delayed-type hypersensitivity reactions (e.g.,poison ivy dermatitis), pneumonia, respiratory tract inflammation, AdultRespiratory Distress Syndrome (ARDS), encephalitis, immediatehypersensitivity reactions, asthma, hayfever, allergies, acuteanaphylaxis, rheumatic fever, glomerulonephritis, pyelonephritis,cellulitis, cystitis, chronic cholecystitis, ischemia (ischemic injury),reperfusion injury, allograft rejection, host-versus-graft rejection,appendicitis, arteritis, blepharitis, bronchiolitis, bronchitis,cervicitis, cholangitis, chorioamnionitis, conjunctivitis,dacryoadenitis, dermatomyositis, endocarditis, endometritis, enteritis,enterocolitis, epicondylitis, epididymitis, fasciitis, fibrositis,gastritis, gastroenteritis, gingivitis, ileitis, iritis, laryngitis,myelitis, myocarditis, nephritis, omphalitis, oophoritis, orchitis,osteitis, otitis, pancreatitis, parotitis, pericarditis, pharyngitis,pleuritis, phlebitis, pneumonitis, proctitis, prostatitis, rhinitis,salpingitis, sinusitis, stomatitis, synovitis, testitis, tonsillitis,urethritis, urocystitis, uveitis, vaginitis, vasculitis, vulvitis,vulvovaginitis, angitis, chronic bronchitis, osteomyelitis, opticneuritis, temporal arteritis, transverse myelitis, necrotizingfasciitis, and necrotizing enterocolitis. An ocular inflammatory diseaseincludes, but is not limited to, post-surgical inflammation.

An “autoimmune disease” refers to a disease arising from aninappropriate immune response of the body of a subject againstsubstances and tissues normally present in the body. In other words, theimmune system mistakes some part of the body as a pathogen and attacksits own cells. This may be restricted to certain organs (e.g., inautoimmune thyroiditis) or involve a particular tissue in differentplaces (e.g., Goodpasture's disease which may affect the basementmembrane in both the lung and kidney). The treatment of autoimmunediseases is typically with immunosuppression, e.g., medications whichdecrease the immune response. Exemplary autoimmune diseases include, butare not limited to, glomerulonephritis, Goodpasture's syndrome,necrotizing vasculitis, lymphadenitis, peri-arteritis nodosa, systemiclupus erythematosis, rheumatoid, arthritis, psoriatic arthritis,systemic lupus erythematosis, psoriasis, ulcerative colitis, systemicsclerosis, dermatomyositis/polymyositis, anti-phospholipid antibodysyndrome, scleroderma, pemphigus vulgaris, ANCA-associated vasculitis(e.g., Wegener's granulomatosis, microscopic polyangiitis), uveitis,Sjogren's syndrome, Crohn's disease, Reiter's syndrome, ankylosingspondylitis, Lyme disease, Guillain-Barre syndrome, Hashimoto'sthyroiditis, and cardiomyopathy.

The term “liver disease” or “hepatic disease” refers to damage to or adisease of the liver. Non-limiting examples of liver disease includeintrahepatic cholestasis (e.g., alagille syndrome, biliary livercirrhosis), fatty liver (e.g., alcoholic fatty liver, Reye's syndrome),hepatic vein thrombosis, hepatolenticular degeneration (i.e., Wilson'sdisease), hepatomegaly, liver abscess (e.g., amebic liver abscess),liver cirrhosis (e.g., alcoholic, biliary, and experimental livercirrhosis), alcoholic liver diseases (e.g., fatty liver, hepatitis,cirrhosis), parasitic liver disease (e.g., hepatic echinococcosis,fascioliasis, amebic liver abscess), jaundice (e.g., hemolytic,hepatocellular, cholestatic jaundice), cholestasis, portal hypertension,liver enlargement, ascites, hepatitis (e.g., alcoholic hepatitis, animalhepatitis, chronic hepatitis (e.g., autoimmune, hepatitis B, hepatitisC, hepatitis D, drug induced chronic hepatitis), toxic hepatitis, viralhuman hepatitis (e.g., hepatitis A, hepatitis B, hepatitis C, hepatitisD, hepatitis E), granulomatous hepatitis, secondary biliary cirrhosis,hepatic encephalopathy, varices, primary biliary cirrhosis, primarysclerosing cholangitis, hepatocellular adenoma, hemangiomas, bilestones, liver failure (e.g., hepatic encephalopathy, acute liverfailure), angiomyolipoma, calcified liver metastases, cystic livermetastases, fibrolamellar hepatocarcinoma, hepatic adenoma, hepatoma,hepatic cysts (e.g., Simple cysts, Polycystic liver disease,hepatobiliary cystadenoma, choledochal cyst), mesenchymal tumors(mesenchymal hamartoma, infantile hemangioendothelioma, hemangioma,peliosis hepatis, lipomas, inflammatory pseudotumor), epithelial tumors(e.g., bile duct hamartoma, bile duct adenoma), focal nodularhyperplasia, nodular regenerative hyperplasia, hepatoblastoma,hepatocellular carcinoma, cholangiocarcinoma, cystadenocarcinoma, tumorsof blood vessels, angiosarcoma, Karposi's sarcoma, hemangioendothelioma,embryonal sarcoma, fibrosarcoma, leiomyosarcoma, rhabdomyosarcoma,carcinosarcoma, teratoma, carcinoid, squamous carcinoma, primarylymphoma, peliosis hepatis, erythrohepatic porphyria, hepatic porphyria(e.g., acute intermittent porphyria, porphyria cutanea tarda), andZellweger syndrome.

The term “spleen disease” refers to a disease of the spleen. Example ofspleen diseases include, but are not limited to, splenomegaly, spleencancer, asplenia, spleen trauma, idiopathic purpura, Felty's syndrome,Hodgkin's disease, and immune-mediated destruction of the spleen.

The term “lung disease” or “pulmonary disease” refers to a disease ofthe lung. Examples of lung diseases include, but are not limited to,bronchiectasis, bronchitis, bronchopulmonary dysplasia, interstitiallung disease, occupational lung disease, emphysema, cystic fibrosis,acute respiratory distress syndrome (ARDS), severe acute respiratorysyndrome (SARS), asthma (e.g., intermittent asthma, mild persistentasthma, moderate persistent asthma, severe persistent asthma), chronicbronchitis, chronic obstructive pulmonary disease (COPD), emphysema,interstitial lung disease, sarcoidosis, asbestosis, aspergilloma,aspergillosis, pneumonia (e.g., lobar pneumonia, multilobar pneumonia,bronchial pneumonia, interstitial pneumonia), pulmonary fibrosis,pulmonary tuberculosis, rheumatoid lung disease, pulmonary embolism, andlung cancer (e.g., non-small-cell lung carcinoma (e.g., adenocarcinoma,squamous-cell lung carcinoma, large-cell lung carcinoma), small-celllung carcinoma).

A “hematological disease” includes a disease which affects ahematopoietic cell or tissue. Hematological diseases include diseasesassociated with aberrant hematological content and/or function. Examplesof hematological diseases include diseases resulting from bone marrowirradiation or chemotherapy treatments for cancer, diseases such aspernicious anemia, hemorrhagic anemia, hemolytic anemia, aplasticanemia, sickle cell anemia, sideroblastic anemia, anemia associated withchronic infections such as malaria, trypanosomiasis, HTV, hepatitisvirus or other viruses, myelophthisic anemias caused by marrowdeficiencies, renal failure resulting from anemia, anemia, polycythemia,infectious mononucleosis (EVI), acute non-lymphocytic leukemia (ANLL),acute myeloid leukemia (AML), acute promyelocytic leukemia (APL), acutemyelomonocytic leukemia (AMMoL), polycythemia vera, lymphoma, acutelymphocytic leukemia (ALL), chronic lymphocytic leukemia, Wilm's tumor,Ewing's sarcoma, retinoblastoma, hemophilia, disorders associated withan increased risk of thrombosis, herpes, thalassemia, antibody-mediateddisorders such as transfusion reactions and erythroblastosis, mechanicaltrauma to red blood cells such as micro-angiopathic hemolytic anemias,thrombotic thrombocytopenic purpura and disseminated intravascularcoagulation, infections by parasites such as Plasmodium, chemicalinjuries from, e.g., lead poisoning, and hypersplenism.

The term “neurological disease” refers to any disease of the nervoussystem, including diseases that involve the central nervous system(brain, brainstem and cerebellum), the peripheral nervous system(including cranial nerves), and the autonomic nervous system (parts ofwhich are located in both central and peripheral nervous system).Neurodegenerative diseases refer to a type of neurological diseasemarked by the loss of nerve cells, including, but not limited to,Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis,tauopathies (including frontotemporal dementia), and Huntington'sdisease. Examples of neurological diseases include, but are not limitedto, headache, stupor and coma, dementia, seizure, sleep disorders,trauma, infections, neoplasms, neuro-ophthalmology, movement disorders,demyelinating diseases, spinal cord disorders, and disorders ofperipheral nerves, muscle and neuromuscular junctions. Addiction andmental illness, include, but are not limited to, bipolar disorder andschizophrenia, are also included in the definition of neurologicaldiseases. Further examples of neurological diseases include acquiredepileptiform aphasia; acute disseminated encephalomyelitis;adrenoleukodystrophy; agenesis of the corpus callosum; agnosia; Aicardisyndrome; Alexander disease; Alpers' disease; alternating hemiplegia;Alzheimer's disease; amyotrophic lateral sclerosis; anencephaly;Angelman syndrome; angiomatosis; anoxia; aphasia; apraxia; arachnoidcysts; arachnoiditis; Arnold-Chiari malformation; arteriovenousmalformation; Asperger syndrome; ataxia telangiectasia; attentiondeficit hyperactivity disorder, autism; autonomic dysfunction; backpain; Batten disease; Behcet's disease; Bell's palsy; benign essentialblepharospasm; benign focal; amyotrophy; benign intracranialhypertension; Binswanger's disease; blepharospasm; Bloch Sulzbergersyndrome; brachial plexus injury; brain abscess; bbrain injury; braintumors (including glioblastoma multiforme); spinal tumor; Brown-Sequardsyndrome; Canavan disease; carpal tunnel syndrome (CTS); causalgia;central pain syndrome; central pontine myelinolysis; cephalic disorder,cerebral aneurysm; cerebral arteriosclerosis; cerebral atrophy; cerebralgigantism; cerebral palsy; Charcot-Marie-Tooth disease;chemotherapy-induced neuropathy and neuropathic pain; Chiarimalformation; chorea; chronic inflammatory demyelinating polyneuropathy(CIDP); chronic pain; chronic regional pain syndrome; Coffin Lowrysyndrome; coma, including persistent vegetative state; congenital facialdiplegia; corticobasal degeneration; cranial arteritis;craniosynostosis; Creutzfeldt-Jakob disease; cumulative traumadisorders; Cushing's syndrome; cytomegalic inclusion body disease(CIBD); cytomegalovirus infection; dancing eyes-dancing feet syndrome;Dandy-Walker syndrome; Dawson disease; De Morsier's syndrome;Dejerine-Klumpke palsy; dementia; dermatomyositis; diabetic neuropathy;diffuse sclerosis; dysautonomia; dysgraphia; dyslexia; dystonias; earlyinfantile epileptic encephalopathy; empty sella syndrome; encephalitis;encephaloceles; encephalotrigeminal angiomatosis; epilepsy; Erb's palsy;essential tremor, Fabry's disease; Fahr's syndrome; fainting; familialspastic paralysis; febrile seizures; Fisher syndrome; Friedreich'sataxia; frontotemporal dementia and other “tauopathies”; Gaucher'sdisease; Gerstmann's syndrome; giant cell arteritis; giant cellinclusion disease; globoid cell leukodystrophy; Guillain-Barre syndrome;HTLV-1 associated myelopathy; Hallervorden-Spatz disease; head injury;headache; hemifacial spasm; hereditary spastic paraplegia; heredopathiaatactica polyneuritiformis; herpes zoster oticus; herpes zoster,Hirayama syndrome; HIV-associated dementia and neuropathy (see alsoneurological manifestations of AIDS); holoprosencephaly; Huntington'sdisease and other polyglutamine repeat diseases; hydranencephaly;hydrocephalus; hypercortisolism; hypoxia; immune-mediatedencephalomyelitis; inclusion body myositis; incontinentia pigmenti;infantile; phytanic acid storage disease; Infantile Refsum disease;infantile spasms; inflammatory myopathy; intracranial cyst; intracranialhypertension; Joubert syndrome; Kearns-Sayre syndrome; Kennedy disease;Kinsbourne syndrome; Klippel Feil syndrome; Krabbe disease;Kugelberg-Welander disease; kuru; Lafora disease; Lambert-Eatonmyasthenic syndrome; Landau-Kleffner syndrome; lateral medullary(Wallenberg) syndrome; learning disabilities; Leigh's disease;Lennox-Gastaut syndrome; Lesch-Nyhan syndrome; leukodystrophy; Lewy bodydementia; lissencephaly; locked-in syndrome; Lou Gehrig's disease (akamotor neuron disease or amyotrophic lateral sclerosis); lumbar discdisease; lyme disease-neurological sequelae; Machado-Joseph disease;macrencephaly; megalencephaly; Melkersson-Rosenthal syndrome; Menieresdisease; meningitis; Menkes disease; metachromatic leukodystrophy;microcephaly; migraine; Miller Fisher syndrome; mini-strokes;mitochondrial myopathies; Mobius syndrome; monomelic amyotrophy; motorneurone disease; moyamoya disease; mucopolysaccharidoses; multi-infarctdementia; multifocal motor neuropathy; multiple sclerosis and otherdemyelinating disorders; multiple system atrophy with posturalhypotension; muscular dystrophy; myasthenia gravis; myelinoclasticdiffuse sclerosis; myoclonic encephalopathy of infants; myoclonus;myopathy; myotonia congenital; narcolepsy; neurofibromatosis;neuroleptic malignant syndrome; neurological manifestations of AIDS;neurological sequelae of lupus; neuromyotonia; neuronal ceroidlipofuscinosis; neuronal migration disorders; Niemann-Pick disease;O'Sullivan-McLeod syndrome; occipital neuralgia; occult spinaldysraphism sequence; Ohtahara syndrome; olivopontocerebellar atrophy;opsoclonus myoclonus; optic neuritis; orthostatic hypotension; overusesyndrome; paresthesia; Parkinson's disease; paramyotonia congenita;paraneoplastic diseases; paroxysmal attacks; Parry Romberg syndrome;Pelizaeus-Merzbacher disease; periodic paralyses; peripheral neuropathy;painful neuropathy and neuropathic pain; persistent vegetative state;pervasive developmental disorders; photic sneeze reflex; phytanic acidstorage disease; Pick's disease; pinched nerve; pituitary tumors;polymyositis; porencephaly; Post-Polio syndrome; postherpetic neuralgia(PHN); postinfectious encephalomyelitis; postural hypotension;Prader-Willi syndrome; primary lateral sclerosis; prion diseases;progressive; hemifacial atrophy; progressive multifocalleukoencephalopathy; progressive sclerosing poliodystrophy; progressivesupranuclear palsy; pseudotumor cerebri; Ramsay-Hunt syndrome (Type Iand Type II); Rasmussen's Encephalitis; reflex sympathetic dystrophysyndrome; Refsum disease; repetitive motion disorders; repetitive stressinjuries; restless legs syndrome; retrovirus-associated myelopathy; Rettsyndrome; Reye's syndrome; Saint Vitus Dance; Sandhoff disease;Schilder's disease; schizencephaly; septo-optic dysplasia; shaken babysyndrome; shingles; Shy-Drager syndrome; Sjogren's syndrome; sleepapnea; Soto's syndrome; spasticity; spina bifida; spinal cord injury;spinal cord tumors; spinal muscular atrophy; stiff-person syndrome;stroke; Sturge-Weber syndrome; subacute sclerosing panencephalitis;subarachnoid hemorrhage; subcortical arteriosclerotic encephalopathy;sydenham chorea; syncope; syringomyelia; tardive dyskinesia; Tay-Sachsdisease; temporal arteritis; tethered spinal cord syndrome; Thomsendisease; thoracic outlet syndrome; tic douloureux; Todd's paralysis;Tourette syndrome; transient ischemic attack; transmissible spongiformencephalopathies; transverse myelitis; traumatic brain injury; tremor;trigeminal neuralgia; tropical spastic paraparesis; tuberous sclerosis;vascular dementia (multi-infarct dementia); vasculitis includingtemporal arteritis; Von Hippel-Lindau Disease (VHL); Wallenberg'ssyndrome; Werdnig-Hoffman disease; West syndrome; whiplash; Williamssyndrome; Wilson's disease; and Zellweger syndrome.

A “painful condition” includes, but is not limited to, neuropathic pain(e.g., peripheral neuropathic pain), central pain, deafferentiationpain, chronic pain (e.g., chronic nociceptive pain, and other forms ofchronic pain such as post-operative pain, e.g., pain arising after hip,knee, or other replacement surgery), pre-operative pain, stimulus ofnociceptive receptors (nociceptive pain), acute pain (e.g., phantom andtransient acute pain), noninflammatory pain, inflammatory pain, painassociated with cancer, wound pain, burn pain, postoperative pain, painassociated with medical procedures, pain resulting from pruritus,painful bladder syndrome, pain associated with premenstrual dysphoricdisorder and/or premenstrual syndrome, pain associated with chronicfatigue syndrome, pain associated with pre-term labor, pain associatedwith withdrawl symptoms from drug addiction, joint pain, arthritic pain(e.g., pain associated with crystalline arthritis, osteoarthritis,psoriatic arthritis, gouty arthritis, reactive arthritis, rheumatoidarthritis or Reiter's arthritis), lumbosacral pain, musculo-skeletalpain, headache, migraine, muscle ache, lower back pain, neck pain,toothache, dental/maxillofacial pain, visceral pain and the like. One ormore of the painful conditions contemplated herein can comprise mixturesof various types of pain provided above and herein (e.g. nociceptivepain, inflammatory pain, neuropathic pain, etc.). In some embodiments, aparticular pain can dominate. In other embodiments, the painfulcondition comprises two or more types of pains without one dominating. Askilled clinician can determine the dosage to achieve a therapeuticallyeffective amount for a particular subject based on the painfulcondition.

The term “psychiatric disorder” refers to a disease of the mind andincludes diseases and disorders listed in the Diagnostic and StatisticalManual of Mental Disorders—Fourth Edition (DSM-IV), published by theAmerican Psychiatric Association, Washington D. C. (1994). Psychiatricdisorders include, but are not limited to, anxiety disorders (e.g.,acute stress disorder agoraphobia, generalized anxiety disorder,obsessive-compulsive disorder, panic disorder, posttraumatic stressdisorder, separation anxiety disorder, social phobia, and specificphobia), childhood disorders, (e.g., attention-deficit/hyperactivitydisorder, conduct disorder, and oppositional defiant disorder), eatingdisorders (e.g., anorexia nervosa and bulimia nervosa), mood disorders(e.g., depression, bipolar disorder, cyclothymic disorder, dysthymicdisorder, and major depressive disorder), personality disorders (e.g.,antisocial personality disorder, avoidant personality disorder,borderline personality disorder, dependent personality disorder,histrionic personality disorder, narcissistic personality disorder,obsessive-compulsive personality disorder, paranoid personalitydisorder, schizoid personality disorder, and schizotypal personalitydisorder), psychotic disorders (e.g., brief psychotic disorder,delusional disorder, schizoaffective disorder, schizophreniformdisorder, schizophrenia, and shared psychotic disorder),substance-related disorders (e.g., alcohol dependence, amphetaminedependence, cannabis dependence, cocaine dependence, hallucinogendependence, inhalant dependence, nicotine dependence, opioid dependence,phencyclidine dependence, and sedative dependence), adjustment disorder,autism, delirium, dementia, multi-infarct dementia, learning and memorydisorders (e.g., amnesia and age-related memory loss), and Tourette'sdisorder.

The term “metabolic disorder” refers to any disorder that involves analteration in the normal metabolism of carbohydrates, lipids, proteins,nucleic acids, or a combination thereof. A metabolic disorder isassociated with either a deficiency or excess in a metabolic pathwayresulting in an imbalance in metabolism of nucleic acids, proteins,lipids, and/or carbohydrates. Factors affecting metabolism include, andare not limited to, the endocrine (hormonal) control system (e.g., theinsulin pathway, the enteroendocrine hormones including GLP-1, PYY orthe like), the neural control system (e.g., GLP-1 in the brain), or thelike. Examples of metabolic disorders include, but are not limited to,diabetes (e.g., type 1 diabetes, type 2 diabetes, gestational diabetes),hyperglycemia, hyperinsulinemia, insulin resistance, and obesity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows that ligand B-2 and Pd(NO₃)₂ formed a gel. Some instancesof divalent linker

were omitted for clarity. FIG. 1B, top panel, shows an exemplary protonnuclear magnetic resonance (¹H NMR) spectrum (400 MHz, DMSO-d₆) ofligand A-1. FIG. 1B, bottom panel, shows that ligand A-1 and Pd(NO₃)₂formed nanosphere I-1. FIG. 1C shows an exemplary ¹H NMR spectrum (400MHz) of a gel formed by heating at 80° C. overnight a solution of ligandB-2 (0.01 M) and Pd(NO₃)₂ in DMSO-d₆ (top panel) and an exemplary ¹H NMRspectrum (400 MHz, DMSO-d₆) of nanosphere I-1 (bottom panel).

FIG. 2A shows exemplary gelation kinetics results of a reaction(gelation) mixture of FIG. 1A as indicated by rheology of the reactionmixture at different reaction times. The concentration of ligand B-2 inDMSO-d₆ was 0.024 M; w was 10 rad/s; 1% strain. G′: shear storagemodulus. G″: shear loss modulus. FIG. 2B shows an image of the equipmentemployed in FIG. 2A. FIG. 2C shows a proposed two-stage mechanism of thegelation of FIG. 2A. Stage i: initial disordered network formation.Stage ii: thermal equilibration to form the gel. Primary loops formed inthe process are highlighted in red.

FIGS. 3A and 3B show exemplary ¹H NMR spectra of the reaction mixturesof FIG. 1A, except the reaction temperature and time duration, whichwere as provided in FIGS. 3A and 3B.

FIG. 4A shows the effects of concentration (in millimoles of ligand B-2per liter of DMSO-d₆) on gelation of reactions of FIG. 1A, wherein thereaction temperature was room temperature. FIG. 4B shows the effects ofconcentration (in millimoles of ligand B-2 per liter of DMSO-d₆) ongelation of reactions of FIG. 1A. Gels at room temperature remained gelsafter annealing. Gelation took place at concentrations as low as 0.014M. FIG. 4C shows the dependence of storage and loss modulus of a gel onthe concentration of ligand B-2 of the gel.

FIG. 5A shows exemplary rheology of gels formed from macromer B-2. FIG.5B shows the storage and loss modulus of a gel formed by a reaction ofFIG. 1A, wherein ligand B-2 was partially replaced with ligand A-1,wherein the mole amount of ligand A-1 was twice the mole amount ofligand B-2 that was replaced by ligand A-1. FIG. 5C shows the shearviscosity of the gels of FIG. 5B.

FIG. 6A shows the chemical structure of doxorubicin. FIG. 6B is aphotograph of a gel formed by heating in DMSO-d₆ at 70° C. for 1 day asolution of ligand B-2 (100 mM) and Pd(NO₃)₂ in the presence ofdoxorubicin (12 equivalents relative to the expected amount of thenanospheres (M₁₂L₂₄) formed from B-2 and Pd(NO₃)₂; 100 mM). FIG. 6C is aphotograph of the gel after extracting the gel of FIG. 6B four timeswith DMSO-d₆. FIG. 6D are photographs of the four extracts of FIG. 6C.From left to right; the first to fourth extracts.

FIG. 7: a scheme showing the release of tryptamine glycnamide from a gelof Example 18 by treating the gel with chymotrypsin. The details areshown in Example 19.

FIG. 8 shows exemplary strain sweeps at ω=100 rad/s of a gel formed atroom temperature. The reactants were B-2 and Pd(NO₃)₂.2H₂O, which weremixed in DMSO-d₆ at room temperature to form a gel where theconcentration of B-2 is 0.024 M. G′: shear storage modulus. G″: shearloss modulus.

FIGS. 9A and 9B show exemplary ¹H NMR spectra (DMSO-d₆) of gels III-5(FIG. 9A) and III-6 (FIG. 9B).

FIG. 10: release of doxorubicin from the gel of Example 17. The detailsare shown in Example 18.

FIG. 11A shows the changes in shear viscosity of a reaction mixture ofFIG. 15A over reaction time. FIG. 11B is a plot of storage modulus (G′)and loss modulus (G″) of a gel of FIG. 15A versus the strain (ω) of thegel.

FIG. 12 is an exemplary ¹H NMR spectrum (DMSO-d₆, 400 MHz) of ligandB-1.

FIG. 13A illustrates the formation of a loopy nanosphere by reactingligand B-1 with Pd(NO₃)₂.H₂O. FIG. 13B shows exemplary dynamic lightscattering (DLS) results of dialyzed loopy nanospheres.

FIG. 14 shows exemplary MTT proliferation assay results of nanosphereI-1 using HeLa cells.

FIG. 15A shows the formation of supramolecular complexes and gels usingligand C-1 and Ni(ClO₄)₂. FIG. 15B shows exemplary frequency sweepresults of the reaction mixture at different reaction times. FIG. 15C isa cartoon illustrating a proposed structure of the formed supramolecularcomplexes and gels, where the black bands represent divalent linkers ofthe formula:

FIG. 16A: Schematic representations of traditional polymer metallogels(left panel) compared to suprametallogels (right panel). FIG. 16B:Chemical structures of exemplary ligands described herein along with theeffect of ligand bite angle on the self-assembly of these ligands intosupramolecular nanostructures. The “Fujita cage” and paddlewheelstructures (far left panel and far right panel, respectively) wereobtained from molecular dynamics simulations. FIG. 16C: Chemicalstructures of exemplary macromers B-3 (left panel) and B-4 (right panel)described herein.

FIG. 17A: Aromatic regions of the ¹H NMR spectra (400 MHz, DMSO-d⁶, 25°C.) of, from top to bottom, L1, the initial mixture of L1 andPd(NO₃)₂.2H₂O prepared at room temperature, and the same mixture afterthermal annealing. FIG. 17B: Aromatic regions of the ¹H NMR spectra (400MHz, DMSO-d⁶, 25° C.) of, from top to bottom, L2, the initial mixture ofL2 and Pd(NO₃)₂.2H₂O prepared at room temperature, and the same mixtureafter thermal annealing. FIG. 17C: Low-quality crystal structure of(L2)₄Pd^(II) ₂. Note that due to significant disorder this structure wasnot used to analyze bond lengths and/or angles. However, the paddlewheelconnectivity of the complex was confidently assigned.

FIG. 18: VT ¹H ssNMR spectroscopy (500 MHz, DMSO-d⁶, magic anglespinning at 10 kHz) of the gel derived from paddlewheel-former B-4([B-4]=24 mM) before (top panel) and after (bottom panel) annealing.“2”: B-4.

FIG. 19A: Aromatic region of the ¹H NMR (400 MHz, DMSO-d⁶) spectrum ofthe M₁₂L₂₄ spheres derived from B-3 at high dilution (4.4 mM). Inset:Cryo-TEM image of the soluble aggregates of M₁₂L₂₄ spheres dialyzedagainst Millipore water exhibits ˜30-nm spherical particles. FIG. 19B:Aromatic region of the ¹H ssNMR (500 MHz, DMSO-d⁶, magic angle spinningat 10 kHz) spectrum of the corresponding gel when [B-3]=24 mM. Inset: apicture of the gel.

FIG. 20A: Snapshots illustrating the assembly of metal-ligand clustersfor different ligand species, each initialized from randomconfigurations at time t=0. Images from left to right correspond to theassembly of Pd²⁺ and L-para, L-meta, B-3, and B-4, respectively. For thesuprametallogels prepared from macromers B-3 and B-4, grey linesindicate a likely configuration of the 2.2 kDa PEG chain, which isdescribed implicitly in the simulations.

FIG. 20B: Average cluster size as a function of time for systems withL-para, L-meta, and macromers B-3 and B-4. Data is plotted in black orgrey to indicate L-para or L-meta based ligands, respectively. Lines orpoints (circles and squares) are used to differentiate free ligands frommacromers, respectively. “Macromer 1”: B-3. “Macromer 2”: B-4.

FIG. 20C: Distribution of cluster sizes for systems with L-para andL-meta ligands are plotted with black or grey bars, respectively. Thedata representing suprametallogels from macromers B-3 and B-4 areplotted with points using the same color and symbol conventions as inFIG. 20B. Inset highlights a narrower data range for the free ligandsL-para and L-meta only. “Macromer 1”: B-3. “Macromer 2”: B-4.

FIG. 20D: Average density of primary loops as a function of cluster sizein suprametallogels from macromers B-3 and B-4 plotted using the samecolor and symbol convention as in FIG. 20B. The black line indicates thepredicted density of loops if clusters are assembled from randomlyselected ligands. Arrows provide the approximate y (cluster size) after1 μs for suprametallogels prepared from B-3 and B-4 (as obtained fromFIG. 20B); they indicate the fraction of looped chains in the respectivesuprametallogel. “Macromer 1”: B-3. “Macromer 2”: B-4.

FIGS. 21A and 21B: Frequency sweeps in oscillatory rheology at 1.0%strain amplitude before and after annealing for 4 h at 80° C. for gelsderived from B-3 ([B-3]=24 mM, FIG. 21A) and B-4 ([B-4]=24 mM, FIG.21B). Stress vs. strain plots before and after thermal annealing forgels derived from B-3 ([B-3]=24 mM, FIG. 21C) and B-4 ([B-4]=24 mM, FIG.21D). Black arrows indicate points used for the determination of theyield stresses and strains. “1”: B-3. “2”: B-4.

FIG. 22A to 22C show images of a gel derived from B-3 ([B-3]=24 mM) asprepared (FIG. 22A), after cutting (FIG. 22B), and after annealing for 4h at 80° C. (FIG. 22C), respectively. The damage emphasized by the greybox was not healed. FIG. 22D to 22F show images of a gel derived fromB-4 ([B-4]=24 mM) as prepared (FIG. 22D), after cutting (FIG. 22E), andafter annealing for 4 h at 80° C. (FIG. 22F), respectively. The damageemphasized by the grey box was healed. In all cases, the images shownare photographs of the bottom of 1-dram vials containing the gels. Nosolvent was added or pressure applied to facilitate healing. FIG. 22G:representative images of suprametallogels from B-3 and B-4 afterswelling for 5 days in DMSO. The swelling ratios (S₁ and S₂=mass ofswollen gel/mass of dry gel) are provided. FIG. 22H: images ofsuprametallogels derived from B-3 and B-4 in the presence of pyrene.Images were taken after continuous washing of the gels with fresh DMSOfor two days. Superior retention of pyrene in the paddlewheel-based gelis readily observed. “1”: B-3. “2”: B-4.

FIG. 23A: images of gels formed from mixing C-1 and iron perchlorate(left panel) or nickel perchlorate (right panel) in acetonitrile.

FIG. 23B: an image of a liquid mixture formed after 25 μL of a 0.05 MK₄EDTA aqueous solution was added to the gel shown in FIG. 23A leftpanel (left panel); and an image of a liquid mixture formed after 25 μLof a 0.05 M K₄EDTA aqueous solution was added to the gel shown in FIG.23A right panel (right panel).

FIGS. 24A and 24B: mechanical properties of gels formed from C-1 andNi(ClO₄)₂ (“Ni”) and Fe(ClO₄)₂(“Fe”) in acetonitrile were characterizedby oscillatory rheology.

FIGS. 25A and 25B: effects of solvents on gelation of the gels formedfrom macromer C-1 and Ni(ClO₄)₂ hydrate.

FIG. 26: oscillatory rheology of the gels of Example 15.

FIG. 27: cytotoxicities of (1) a gel formed from C-2 and Fe²⁺ (“gel”),(2) PEG, and (3) Fe²⁺ (“Fe”) against HeLa cells. MILLIQ water (“milliQ”)used as a control.

FIG. 28: preparation of the gel of Example 17, where the gel containscovalently attached doxorubicin. Inset: an image of the gel.

FIG. 29 shows Formula (I-A), wherein each instance of the black dotrepresents a transition metal ion, each instance of the gray linerepresents a ligand of Formula (A), and each black line represents acoordination bond.

FIG. 30 shows Formula (I-B), wherein each instance of the black dotrepresents a transition metal ion, and each instance of the gray linerepresents a ligand of Formula (A).

FIG. 31 shows a moiety of a nanosphere described herein.

FIG. 32 shows Scheme 8, which shows exemplary synthesis of a paddlewheel(e.g., nano-paddlewheel described herein).

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THE INVENTION

Reversible metal-ligand coordination has emerged as a powerful tool forthe formation of a broad array of materials. In the realm of softmaterials (e.g., gels), reversible metal-ligand coordination is a toolfor the formation of self-healing molecular networks. In the area ofhard materials, reversible metal-ligand coordination enables theformation of metal-organic frameworks (MOFs) and relatedmetallosupramolecular assemblies.

The present disclosure provides, in one aspect, nanostructures formedthrough metal-ligand coordination and junction self-assembly. Thepresent disclosure also provides supramolecular complexes that includenanostructures described herein connected by divalent linkers Y. Theprovided supramolecular complexes are able to swell in various solvents(including water) without dissolution and to form gels. Advantageousover conventional gels (e.g., conventional metallogels), the gelsdescribed herein exhibited excellent mechanical properties withoutsacrificing self-healing. Compared to conventional gels (e.g.,conventional metallogels), the gels described herein behaved as elasticsolids at low oscillatory angular frequencies and showed higherrobustness (e.g., showed higher storage moduli). The nanostructures, andthe nanostructure moieties of a supramolecular complex or gel describedherein, may encapsulate and slowly release an agent (e.g., a smallmolecule, a peptide or protein, or a polynucleotide). Thenanostructures, supramolecular complex, and compositions (e.g., gels)may be useful in delivering effectively and efficiently an agent to asubject, tissue, or cell, as bulk materials (e.g., as super-absorbentmaterials and/or bioactive materials), and/or in increasing thetoughness of composite materials.

Nanostructures

Fujita et al. have reported banana-shaped organic molecules thatself-organize into “Fujita spheres,” which are finite, sphericalcoordination networks with a diameter in the order of nanometers (e.g.,Tominaga et al., Angew. Chem., Int. Ed., 2004, 43, 5621-5625; Bunzen etal. Angew. Chem., Int. Ed. 2012, 51, 3161; Sun et al., Science, 2010,328, 1144). One of such reported Fujita spheres consists of 12equivalents of a central metal ion (e.g., Pd(II)) and 24 equivalents ofa bidentate ligand and has cuboctahedral symmetry. Hupp et al. hasreported metal-organic frameworks prepared from a hexacarboxylatedligand and a transition metal ion (e.g., Cu(II) or Zn(II)) (Eryazici etal., Crystal Growth & Design, 2012, 12, 1075).

One aspect of the present disclosure relates to novel nanostructures,including, but not limited to, nanospheres and nano-paddlewheels. Incertain embodiments, provide herein are nanospheres comprising:

(i) a plurality of a transition metal ion; and

(ii) a plurality of a ligand;

wherein each instance of the transition metal ion and two or moreinstances of the ligand form through coordination bonds a coordinationcomplex;

wherein the plurality of a transition metal ion and the plurality of aligand form through the coordination bonds one substantially sphericalstructure; and

wherein the average outer diameter of the nanosphere is between about 1nm and about 100 nm, inclusive.

In certain embodiments, provide herein are nano-paddlewheels comprising:

(i) a plurality of a transition metal ion; and

(ii) a plurality of a ligand;

wherein each instance of the transition metal ion and two or moreinstances of the ligand form through coordination bonds a coordinationcomplex;

wherein the plurality of a transition metal ion and the plurality of aligand form through the coordination bonds one substantially paddlewheelstructure; and

wherein the average outer diameter of the nano-paddlewheel is betweenabout 1 nm and about 100 nm, inclusive.

In certain embodiments, each instance of the ligand is a monodentateligand. In certain embodiments, each instance of the ligand is apolydentate (e.g., bidentate, tridentate, or tetradentate) ligand. Incertain embodiments, each instance of the ligand comprises two or morepyridinyl moieties. In certain embodiments, each instance of the ligandcomprises at least a first pyridinyl moiety and second pyridinyl moiety,wherein the angle (bite angle) between (1) the lone electron pair of thenitrogen atom of the first pyridinyl moiety and (2) the lone electronpair of the nitrogen atom of the second pyridinyl moiety, along the longaxes of the lone electron pairs, is between 30° and 180°, inclusive,when the ligand is in the minimum energy conformation. In certainembodiments, the bite angle is between 60° and 160°, inclusive (e.g.,about 90°, about 120°, about 127°, or about 149°). In certainembodiments, each instance of the ligand is a polydentate ligand,wherein the shortest distance between two chelation sites of the ligandis between about 5 Å and about 20 Å (e.g., between about 5 Å and about10 Å), inclusive, when the ligand is in the minimum energy conformation.

In certain embodiments, a nanostructure described herein comprises xinstances of a transition metal ion and 2× instances of a ligand ofFormula (A):

A nanostructure described herein includes x instances of a transitionmetal ion. In certain embodiments, all instances of the transition metalion in a nanostructure are the same. In certain embodiments, x is aninteger (e.g., an even integer) between 2 and 48, inclusive. In certainembodiments, x is an integer (e.g., an even integer) between 2 and 30,inclusive. In certain embodiments, x is an integer (e.g., an eveninteger) between 2 and 24, inclusive. In certain embodiments, x is aninteger (e.g., an even integer) between 2 and 18, inclusive. In certainembodiments, x is 2. In certain embodiments, x is 4. In certainembodiments, x is 6. In certain embodiments, x is 12. In certainembodiments, x is 18. In certain embodiments, x is 24. In certainembodiments, x is 30. In certain embodiments, x is 48. In certainembodiments, x is 60. In certain embodiments, x is 12; and thenanostructure is a nanosphere. In certain embodiments, x is 24; and thenanostructure is a nanosphere. In certain embodiments, x is 2; and thenanostructure is a nano-paddlewheel. In certain embodiments, eachinstance of the transition metal ion is Pd (e.g., Pd(II)). In certainembodiments, each instance of the transition metal ion is Rh (e.g.,Rh(I)). In certain embodiments, each instance of the transition metalion is Ir (e.g., Ir(I)). In certain embodiments, each instance of thetransition metal ion is Ni (e.g., Ni(II)). In certain embodiments, eachinstance of the transition metal ion is Pt (e.g., Pt(II)). In certainembodiments, each instance of the transition metal ion is Fe (e.g.,Fe(II) or Fe(III)). In certain embodiments, each instance of thetransition metal ion is Au (e.g., Au(III)). In certain embodiments, eachinstance of the transition metal ion is Cd (e.g., Cd(II)), Co (e.g.,Co(III)), or Cu (e.g., Cu(I) or Cu(II)). In certain embodiments, eachinstance of the transition metal ion is Zn(II). In certain embodiments,each instance of the transition metal ion is not Zn(II).

A nanostructure described herein also includes 2x instances of a ligandof Formula (A). In certain embodiments, all instances of the ligand ofFormula (A) in a nanostructure are the same. In other embodiments, atleast two instances of the ligand of Formula (A) in a nanostructure aredifferent.

Formula (A) includes Ring A that includes X^(A), X^(B), X^(C), X^(D),and X^(E) in the ring system and is unsubstituted (e.g., each instanceof R^(A1) and R^(A2) is hydrogen) or substituted with one or moresubstituents R^(A1) and/or R^(A2) (e.g., at least one instance of R^(A1)or R^(A2) is not hydrogen). In certain embodiments, each instance ofX^(A), X^(B), X^(C), X^(D), and X^(E) is independently C or CR^(A2), andRing A is a substituted or unsubstituted phenyl ring. In certainembodiments, Ring A is of the formula:

In certain embodiments, Ring A is of the formula:

In certain embodiments, Ring A is of the formula:

In certain embodiments, Ring A is of the formula:

In certain embodiments, each instance of X^(A), X^(B), X^(C), and X^(D)is independently O, S, N, NR^(A1), C, or CR^(A2); at least one of X^(A),X^(B), X^(C), and X^(D) is not C or CR^(A2); X^(E) is absent; and Ring Ais a substituted or unsubstituted, 5-membered, monocyclic heteroarylring. In certain embodiments, Ring A is a substituted or unsubstitutedfuranyl, substituted or unsubstituted thienyl, or substituted orunsubstituted pyrrolyl ring. In certain embodiments, Ring A is of theformula:

In certain embodiments, Ring A is a pyrazolyl, imidazolyl, oxazolyl,isoxazolyl, thiazolyl, or isothiazolyl ring, each of which isunsubstituted or substituted with R^(A2). In certain embodiments, eachinstance of X^(A), X^(B), X^(C), and X^(D) is independently O, S, N,NR^(A1), C, or CR^(A2); X^(E) is N, C, or CR^(A2); at least one ofX^(A), X^(B), X^(C), X^(D), and X^(E) is not C or CR^(A2); and Ring A isa substituted or unsubstituted, 6-membered, monocyclic heteroaryl ring.In certain embodiments, Ring A is a substituted or unsubstituted pyridylring. In certain embodiments, Ring A is of the formula:

In certain embodiments, Ring A is a substituted or unsubstitutedpyrazinyl, substituted or unsubstituted pyrimidinyl, or substituted orunsubstituted pyridazinyl ring. In certain embodiments, Ring A is of theformula:

In certain embodiments, Ring A is of the formula:

In certain embodiments, Ring A is of the formula:

In certain embodiments, Ring A is of the formula:

In certain embodiments, at least two instances of R^(A1) are differentfrom each other. In certain embodiments, all instances of R^(A1) are thesame. In certain embodiments, at least one instance of R^(A1) ishydrogen. In certain embodiments, each instance of R^(A1) is hydrogen.In certain embodiments, at least one instance of R^(A1) is substitutedalkyl. In certain embodiments, at least one instance of R^(A1) isunsubstituted alkyl. In certain embodiments, at least one instance ofR^(A1) is unsubstituted C₁₋₆ alkyl. In certain embodiments, allinstances of R^(A1) are unsubstituted C₁₋₆ alkyl. In certainembodiments, at least one instance of R^(A1) is substituted C₁₋₆ alkyl.In certain embodiments, at least one instance of R^(A1) is C₁₋₆ alkylsubstituted with at least one halogen. In certain embodiments, at leastone instance of R^(A1) is —CH₃. In certain embodiments, all instances ofR^(A1) are —CH₃. In certain embodiments, at least one instance of R^(A1)is substituted methyl. In certain embodiments, at least one instance ofR^(A1) is —CH₂F, —CHF₂, or —CF₃. In certain embodiments, at least oneinstance of R^(A1) is ethyl, propyl, butyl, pentyl, or hexyl. In certainembodiments, at least one instance of R^(A1) is substituted alkenyl. Incertain embodiments, at least one instance of R^(A1) is unsubstitutedalkenyl. In certain embodiments, at least one instance of R^(A1) issubstituted alkynyl. In certain embodiments, at least one instance ofR^(A1) is unsubstituted alkynyl. In certain embodiments, at least oneinstance of R^(A1) is substituted carbocyclyl. In certain embodiments,at least one instance of R^(A1) is unsubstituted carbocyclyl. In certainembodiments, at least one instance of R^(A1) is saturated carbocyclyl.In certain embodiments, at least one instance of R^(A1) is unsaturatedcarbocyclyl. In certain embodiments, at least one instance of R^(A1) ismonocyclic carbocyclyl. In certain embodiments, at least one instance ofR^(A1) is 3- to 7-membered, monocyclic carbocyclyl. In certainembodiments, at least one instance of R^(A1) is substitutedheterocyclyl. In certain embodiments, at least one instance of R^(A1) isunsubstituted heterocyclyl. In certain embodiments, at least oneinstance of R^(A1) is saturated heterocyclyl. In certain embodiments, atleast one instance of R^(A1) is unsaturated heterocyclyl. In certainembodiments, at least one instance of R^(A1) is heterocyclyl, whereinone, two, or three atoms in the heterocyclic ring system areindependently selected from the group consisting of nitrogen, oxygen,and sulfur. In certain embodiments, at least one instance of R^(A1) ismonocyclic heterocyclyl. In certain embodiments, at least one instanceof R^(A1) is 3- to 7-membered, monocyclic heterocyclyl. In certainembodiments, at least one instance of R^(A1) is substituted aryl. Incertain embodiments, at least one instance of R^(A1) is unsubstitutedaryl. In certain embodiments, at least one instance of R^(A1) is 6- to10-membered aryl. In certain embodiments, at least one instance ofR^(A1) is substituted phenyl. In certain embodiments, at least oneinstance of R^(A1) is unsubstituted phenyl. In certain embodiments, atleast one instance of R^(A1) is substituted heteroaryl. In certainembodiments, at least one instance of R^(A1) is unsubstitutedheteroaryl. In certain embodiments, at least one instance of R^(A1) isheteroaryl, wherein one, two, three, or four atoms in the heteroarylring system are independently selected from the group consisting ofnitrogen, oxygen, and sulfur. In certain embodiments, at least oneinstance of R^(A1) is monocyclic heteroaryl. In certain embodiments, atleast one instance of R^(A1) is 5-membered, monocyclic heteroaryl. Incertain embodiments, at least one instance of R^(A1) is 6-membered,monocyclic heteroaryl. In certain embodiments, at least one instance ofR^(A1) is bicyclic heteroaryl, wherein the point of attachment may be onany atom of the bicyclic heteroaryl ring system, as valency permits. Incertain embodiments, at least one instance of R^(A1) is 9- or10-membered, bicyclic heteroaryl. In certain embodiments, at least oneinstance of R^(A1) is —C(═O)R^(a) (e.g., —C(═O)(substituted orunsubstituted C₁₋₆ alkyl)), —C(═O)OR^(a) (e.g., —C(═O)O(substituted orunsubstituted C₁₋₆ alkyl)), or —C(═O)N(R^(a))₂ (e.g., —C(═O)NH₂,—C(═O)NH(substituted or unsubstituted C₁₋₆ alkyl), or—C(═O)N(substituted or unsubstituted C₁₋₆ alkyl)-(substituted orunsubstituted C₁₋₆ alkyl)). In certain embodiments, at least oneinstance of R^(A1) is a nitrogen protecting group. In certainembodiments, at least one instance of R^(A1) is Bn, Boc, Cbz, Fmoc,trifluoroacetyl, triphenylmethyl, acetyl, or Ts.

Each instance of R^(A1), R^(A2), R^(B), and R^(C) may independentlyinclude one or more substituents R^(a). In certain embodiments, allinstances of R^(a) are the same. In certain embodiments, at least twoinstances of R are different from each other. In certain embodiments, atleast one instance of R^(a) is H. In certain embodiments, each instanceof R^(a) is H. In certain embodiments, at least one instance of R^(a) issubstituted or unsubstituted acyl (e.g., acetyl). In certainembodiments, at least one instance of R^(a) is substituted orunsubstituted alkyl (e.g., substituted or unsubstituted C₁₋₆ alkyl). Incertain embodiments, at least one instance of R^(a) is —CH₃. In certainembodiments, at least one instance of R^(a) is —CF₃, unsubstitutedethyl, perfluoroethyl, unsubstituted propyl, perfluoropropyl,unsubstituted butyl, or perfluorobutyl. In certain embodiments, at leastone instance of R^(a) is substituted or unsubstituted alkenyl (e.g.,substituted or unsubstituted C₁₋₆ alkenyl). In certain embodiments, atleast one instance of R^(a) is substituted or unsubstituted alkynyl(e.g., substituted or unsubstituted C₁₋₆ alkynyl). In certainembodiments, at least one instance of R^(a) is substituted orunsubstituted carbocyclyl (e.g., substituted or unsubstituted,monocyclic, 3- to 7-membered carbocyclyl). In certain embodiments, atleast one instance of R^(a) is substituted or unsubstituted heterocyclyl(e.g., substituted or unsubstituted, monocyclic, 5- to 6-memberedheterocyclyl, wherein one, two, or three atoms in the heterocyclic ringsystem are independently nitrogen, oxygen, or sulfur). In certainembodiments, at least one instance of R^(a) is substituted orunsubstituted aryl (e.g., substituted or unsubstituted, 6- to10-membered aryl). In certain embodiments, at least one instance ofR^(a) is substituted or unsubstituted phenyl. In certain embodiments, atleast one instance of R^(a) is substituted or unsubstituted heteroaryl(e.g., substituted or unsubstituted, monocyclic, 5- to 6-memberedheteroaryl, wherein one, two, three, or four atoms in the heteroarylring system are independently nitrogen, oxygen, or sulfur). In certainembodiments, at least one instance of R^(a) is a nitrogen protectinggroup (e.g., Bn, Boc, Cbz, Fmoc, trifluoroacetyl, triphenylmethyl,acetyl, or Ts) when attached to a nitrogen atom. In certain embodiments,R^(a) is an oxygen protecting group (e.g., silyl, TBDPS, TBDMS, TIPS,TES, TMS, MOM, THP, t-Bu, Bn, allyl, acetyl, pivaloyl, or benzoyl) whenattached to an oxygen atom. In certain embodiments, R^(a) is a sulfurprotecting group (e.g., acetamidomethyl, t-Bu, 3-nitro-2-pyridinesulfenyl, 2-pyridine-sulfenyl, or triphenylmethyl) when attached to asulfur atom. In certain embodiments, two instances of R^(a) are joinedto form a substituted or unsubstituted heterocyclic ring (e.g.,substituted or unsubstituted, monocyclic, 5- to 6-membered heterocyclicring, wherein one, two, or three atoms in the heterocyclic ring systemare independently nitrogen, oxygen, or sulfur). In certain embodiments,two instances of R^(a) are joined to form a substituted or unsubstitutedheteroaryl ring (e.g., substituted or unsubstituted, monocyclic, 5- to6-membered heteroaryl ring, wherein one, two, three, or four atoms inthe heteroaryl ring system are independently nitrogen, oxygen, orsulfur).

In certain embodiments, at least two instances of R^(A2) are differentfrom each other. In certain embodiments, all instances of R^(A2) are thesame. In certain embodiments, at least one instance of R^(A2) ishydrogen. In certain embodiments, each instance of R^(A2) is hydrogen.In certain embodiments, at least one instance of R^(A2) is halogen. Incertain embodiments, at least one instance of R^(A2) is F. In certainembodiments, at least one instance of R^(A2) is Cl. In certainembodiments, at least one instance of R^(A2) is Br. In certainembodiments, at least one instance of R^(A2) is I (iodine). In certainembodiments, at least one instance of R^(A2) is substituted alkyl. Incertain embodiments, at least one instance of R^(A2) is unsubstitutedalkyl. In certain embodiments, at least one instance of R^(A2) isunsubstituted C₁₋₆ alkyl. In certain embodiments, all instances ofR^(A2) are unsubstituted C₁₋₆ alkyl. In certain embodiments, at leastone instance of R^(A2) is substituted C₁₋₆ alkyl. In certainembodiments, at least one instance of R^(A2) is C₁₋₆ alkyl substitutedwith at least one halogen. In certain embodiments, at least one instanceof R^(A2) is —CH₃. In certain embodiments, all instances of R^(A2) are—CH₃. In certain embodiments, at least one instance of R^(A2) issubstituted methyl. In certain embodiments, at least one instance ofR^(A2) is —CH₂F, —CHF₂, or —CF₃. In certain embodiments, at least oneinstance of R^(A2) is ethyl, propyl, butyl, pentyl, or hexyl. In certainembodiments, at least one instance of R^(A2) is substituted alkenyl. Incertain embodiments, at least one instance of R^(A2) is unsubstitutedalkenyl. In certain embodiments, at least one instance of R^(A2) issubstituted alkynyl. In certain embodiments, at least one instance ofR^(A2) is unsubstituted alkynyl. In certain embodiments, at least oneinstance of R^(A2) is substituted carbocyclyl. In certain embodiments,at least one instance of R^(A2) is unsubstituted carbocyclyl. In certainembodiments, at least one instance of R^(A2) is saturated carbocyclyl.In certain embodiments, at least one instance of R^(A2) is unsaturatedcarbocyclyl. In certain embodiments, at least one instance of R^(A2) ismonocyclic carbocyclyl. In certain embodiments, at least one instance ofR^(A2) is 3- to 7-membered, monocyclic carbocyclyl. In certainembodiments, at least one instance of R^(A2) is substitutedheterocyclyl. In certain embodiments, at least one instance of R^(A2) isunsubstituted heterocyclyl. In certain embodiments, at least oneinstance of R^(A2) is saturated heterocyclyl. In certain embodiments, atleast one instance of R^(A2) is unsaturated heterocyclyl. In certainembodiments, at least one instance of R^(A2) is heterocyclyl, whereinone, two, or three atoms in the heterocyclic ring system areindependently selected from the group consisting of nitrogen, oxygen,and sulfur. In certain embodiments, at least one instance of R^(A2) ismonocyclic heterocyclyl. In certain embodiments, at least one instanceof R^(A2) is 3- to 7-membered, monocyclic heterocyclyl. In certainembodiments, at least one instance of R^(A2) is substituted aryl. Incertain embodiments, at least one instance of R^(A2) is unsubstitutedaryl. In certain embodiments, at least one instance of R^(A2) is 6- to10-membered aryl. In certain embodiments, at least one instance ofR^(A2) is substituted phenyl. In certain embodiments, at least oneinstance of R^(A2) is unsubstituted phenyl. In certain embodiments, atleast one instance of R² is substituted heteroaryl. In certainembodiments, at least one instance of R^(A2) is unsubstitutedheteroaryl. In certain embodiments, at least one instance of R^(A2) isheteroaryl, wherein one, two, three, or four atoms in the heteroarylring system are independently selected from the group consisting ofnitrogen, oxygen, and sulfur. In certain embodiments, at least oneinstance of R^(A2) is monocyclic heteroaryl. In certain embodiments, atleast one instance of R^(A2) is 5-membered, monocyclic heteroaryl. Incertain embodiments, at least one instance of R^(A2) is 6-membered,monocyclic heteroaryl. In certain embodiments, at least one instance ofR^(A2) is bicyclic heteroaryl, wherein the point of attachment may be onany atom of the bicyclic heteroaryl ring system, as valency permits. Incertain embodiments, at least one instance of R^(A2) is 9- or10-membered, bicyclic heteroaryl. In certain embodiments, at least oneinstance of R^(A2) is —OR^(a). In certain embodiments, at least oneinstance of R^(A1) is —OH. In certain embodiments, at least one instanceof R^(A2) is —O(substituted or unsubstituted C₁₋₆ alkyl). In certainembodiments, at least one instance of R^(A2) is —OMe. In certainembodiments, at least one instance of R^(A2) is —OEt, —OPr, or —OBu. Incertain embodiments, at least one instance of R^(A2) is —OBn or —OPh. Incertain embodiments, at least one instance of R^(A2) is —SR. In certainembodiments, at least one instance of R^(A2) is —SH. In certainembodiments, at least one instance of R^(A2) is —SMe. In certainembodiments, at least one instance of R^(A1) is —N(R^(a))₂. In certainembodiments, at least one instance of R^(A2) is —NH₂. In certainembodiments, at least one instance of R^(A2) is —NHMe. In certainembodiments, at least one instance of R² is —NMe₂. In certainembodiments, at least one instance of R^(A2) is —CN. In certainembodiments, at least one instance of R^(A2) is —SCN. In certainembodiments, at least one instance of R^(A2) is —C(═NR^(a))R^(a),—C(═NR^(a))OR^(a), or —C(═NR^(a))N(R^(a))₂. In certain embodiments, atleast one instance of R^(A2) is —C(═O)R^(a) or —C(═O)OR^(a). In certainembodiments, at least one instance of R^(A2) is —C(═O)N(R^(a))₂. Incertain embodiments, at least one instance of R^(A2) is —C(═O)NMe₂,—C(═O)NHMe, or —C(═O)NH₂. In certain embodiments, at least one instanceof R^(A2) is —NO₂. In certain embodiments, at least one instance ofR^(A2) is —NR^(a)C(═O)R^(a), —NR^(a)C(═O)OR^(a), or—NR^(a)C(═O)N(R^(a))₂. In certain embodiments, at least one instance ofR^(A2) is —OC(═O)R^(a), —OC(═O)OR^(a), or —OC(═O)N(R^(a))₂.

Formula (A) includes as Ring B a pyridyl ring that is unsubstituted(e.g., when m is 0) or substituted with one or more substituents R^(B)(e.g., when m is 1, 2, 3, or 4). In certain embodiments, Ring B is ofthe formula:

In certain embodiments, Ring B is of the formula:

In certain embodiments, Ring B is of the formula:

In certain embodiments, Ring B is of the formula:

In certain embodiments, Ring B is of the formula:

In certain embodiments, Ring B is of the formula:

In certain embodiments, Ring B is of the formula:

In certain embodiments, Ring B is of the formula:

In certain embodiments, at least two instances of R^(B) are differentfrom each other. In certain embodiments, all instances of R^(B) are thesame. In certain embodiments, at least one instance of R^(B) is halogen.In certain embodiments, at least one instance of R^(B) is F. In certainembodiments, at least one instance of R^(B) is Cl. In certainembodiments, at least one instance of R^(B) is Br. In certainembodiments, at least one instance of R^(B) is I (iodine). In certainembodiments, at least one instance of R^(B) is substituted alkyl. Incertain embodiments, at least one instance of R^(B) is unsubstitutedalkyl. In certain embodiments, at least one instance of R^(B) isunsubstituted C₁₋₆ alkyl. In certain embodiments, all instances of R^(B)are unsubstituted C₁₋₆ alkyl. In certain embodiments, at least oneinstance of R^(B) is substituted C₁₋₆ alkyl. In certain embodiments, atleast one instance of R^(B) is C₁₋₆ alkyl substituted with at least onehalogen. In certain embodiments, at least one instance of R^(B) is —CH₃.In certain embodiments, all instances of R^(B) are —CH₃. In certainembodiments, at least one instance of R^(B) is substituted methyl. Incertain embodiments, at least one instance of R^(B) is —CH₂F, —CHF₂, or—CF₃. In certain embodiments, at least one instance of R^(B) is ethyl,propyl, butyl, pentyl, or hexyl. In certain embodiments, at least oneinstance of R^(B) is substituted alkenyl. In certain embodiments, atleast one instance of R^(B) is unsubstituted alkenyl. In certainembodiments, at least one instance of R^(B) is substituted alkynyl. Incertain embodiments, at least one instance of R^(B) is unsubstitutedalkynyl. In certain embodiments, at least one instance of R^(B) issubstituted carbocyclyl. In certain embodiments, at least one instanceof R^(B) is unsubstituted carbocyclyl. In certain embodiments, at leastone instance of R^(B) is saturated carbocyclyl. In certain embodiments,at least one instance of R^(B) is unsaturated carbocyclyl. In certainembodiments, at least one instance of R^(B) is monocyclic carbocyclyl.In certain embodiments, at least one instance of R^(B) is 3- to7-membered, monocyclic carbocyclyl. In certain embodiments, at least oneinstance of R^(B) is substituted heterocyclyl. In certain embodiments,at least one instance of R^(B) is unsubstituted heterocyclyl. In certainembodiments, at least one instance of R^(B) is saturated heterocyclyl.In certain embodiments, at least one instance of R^(B) is unsaturatedheterocyclyl. In certain embodiments, at least one instance of R^(B) isheterocyclyl, wherein one, two, or three atoms in the heterocyclic ringsystem are independently selected from the group consisting of nitrogen,oxygen, and sulfur. In certain embodiments, at least one instance ofR^(B) is monocyclic heterocyclyl. In certain embodiments, at least oneinstance of R^(B) is 3- to 7-membered, monocyclic heterocyclyl. Incertain embodiments, at least one instance of R^(B) is substituted aryl.In certain embodiments, at least one instance of R^(B) is unsubstitutedaryl. In certain embodiments, at least one instance of R^(B) is 6- to10-membered aryl. In certain embodiments, at least one instance of R^(B)is substituted phenyl. In certain embodiments, at least one instance ofR^(B) is unsubstituted phenyl. In certain embodiments, at least oneinstance of R^(B) is substituted heteroaryl. In certain embodiments, atleast one instance of R^(B) is unsubstituted heteroaryl. In certainembodiments, at least one instance of R^(B) is heteroaryl, wherein one,two, three, or four atoms in the heteroaryl ring system areindependently selected from the group consisting of nitrogen, oxygen,and sulfur. In certain embodiments, at least one instance of R^(B) ismonocyclic heteroaryl. In certain embodiments, at least one instance ofR^(B) is 5-membered, monocyclic heteroaryl. In certain embodiments, atleast one instance of R^(B) is 6-membered, monocyclic heteroaryl. Incertain embodiments, at least one instance of R^(B) is bicyclicheteroaryl, wherein the point of attachment may be on any atom of thebicyclic heteroaryl ring system, as valency permits. In certainembodiments, at least one instance of R^(B) is 9- or 10-membered,bicyclic heteroaryl. In certain embodiments, at least one instance ofR^(B) is —OR^(a). In certain embodiments, at least one instance of R^(B)is —OH. In certain embodiments, at least one instance of R^(B) is—O(substituted or unsubstituted C₁₋₆ alkyl). In certain embodiments, atleast one instance of R^(B) is —OMe. In certain embodiments, at leastone instance of R^(B) is —OEt, —OPr, or —OBu. In certain embodiments, atleast one instance of R^(B) is —OBn or —OPh. In certain embodiments, atleast one instance of R^(B) is —SR. In certain embodiments, at least oneinstance of R^(B) is —SH. In certain embodiments, at least one instanceof R^(B) is —SMe. In certain embodiments, at least one instance of R^(B)is —N(R^(a))₂. In certain embodiments, at least one instance of R^(B) is—NH₂. In certain embodiments, at least one instance of R^(B) is —NHMe.In certain embodiments, at least one instance of R^(B) is —NMe₂. Incertain embodiments, at least one instance of R^(B) is —CN. In certainembodiments, at least one instance of R^(B) is —SCN. In certainembodiments, at least one instance of R^(B) is —C(═NR^(a))R^(a),—C(═NR^(a))OR^(a), or —C(═NR^(a))N(R^(a))₂. In certain embodiments, atleast one instance of R^(B) is —C(═O)R^(a) or —C(═O)OR^(a). In certainembodiments, at least one instance of R^(B) is —C(═O)N(R^(a))₂. Incertain embodiments, at least one instance of R^(B) is —C(═O)NMe₂,—C(═O)NHMe, or —C(═O)NH₂. In certain embodiments, at least one instanceof R^(B) is —NO₂. In certain embodiments, at least one instance of R^(B)is —NR^(a)C(═O)R^(a), —NR^(a)C(═O)OR^(a), or —NR^(a)C(═O)N(R^(a))₂. Incertain embodiments, at least one instance of R^(B) is —OC(═O)R^(a),—OC(═O)OR^(a), or —OC(═O)N(R^(a))₂.

In certain embodiments, m is 0. In certain embodiments, m is 1. Incertain embodiments, m is 2. In certain embodiments, m is 3. In certainembodiments, m is 4.

Formula (A) includes as Ring C a pyridyl ring that is unsubstituted(e.g., when n is 0) or substituted with one or more substituents R^(C)(e.g., when n is 1, 2, 3, or 4). In certain embodiments, Ring C is ofthe formula:

In certain embodiments, Ring C is of the formula:

In certain embodiments, Ring C is of the formula:

In certain embodiments, Ring C is of the formula:

In certain embodiments, Ring C is of the formula:

In certain embodiments, Ring C is of the formula:

In certain embodiments, Ring C is of the formula:

In certain embodiments, at least two instances of R^(C) are differentfrom each other. In certain embodiments, all instances of R^(C) are thesame. In certain embodiments, at least one instance of R^(C) is halogen.In certain embodiments, at least one instance of R^(C) is F. In certainembodiments, at least one instance of R^(C) is Cl. In certainembodiments, at least one instance of R^(C) is Br. In certainembodiments, at least one instance of R^(C) is I (iodine). In certainembodiments, at least one instance of R^(C) is substituted alkyl. Incertain embodiments, at least one instance of R^(C) is unsubstitutedalkyl. In certain embodiments, at least one instance of R^(C) isunsubstituted C₁₋₆ alkyl. In certain embodiments, all instances of R^(C)are unsubstituted C₁₋₆ alkyl. In certain embodiments, at least oneinstance of R^(C) is substituted C₁₋₆ alkyl. In certain embodiments, atleast one instance of R^(C) is C₁₋₆ alkyl substituted with at least onehalogen. In certain embodiments, at least one instance of R^(C) is —CH₃.In certain embodiments, all instances of R^(C) are —CH₃. In certainembodiments, at least one instance of R^(C) is substituted methyl. Incertain embodiments, at least one instance of R^(C) is —CH₂F, —CHF₂, or—CF₃. In certain embodiments, at least one instance of R^(C) is ethyl,propyl, butyl, pentyl, or hexyl. In certain embodiments, at least oneinstance of R^(C) is substituted alkenyl. In certain embodiments, atleast one instance of R^(C) is unsubstituted alkenyl. In certainembodiments, at least one instance of R^(C) is substituted alkynyl. Incertain embodiments, at least one instance of R^(C) is unsubstitutedalkynyl. In certain embodiments, at least one instance of R^(C) issubstituted carbocyclyl. In certain embodiments, at least one instanceof R^(C) is unsubstituted carbocyclyl. In certain embodiments, at leastone instance of R^(C) is saturated carbocyclyl. In certain embodiments,at least one instance of R^(C) is unsaturated carbocyclyl. In certainembodiments, at least one instance of R^(C) is monocyclic carbocyclyl.In certain embodiments, at least one instance of R^(C) is 3- to7-membered, monocyclic carbocyclyl. In certain embodiments, at least oneinstance of R^(C) is substituted heterocyclyl. In certain embodiments,at least one instance of R^(C) is unsubstituted heterocyclyl. In certainembodiments, at least one instance of R^(C) is saturated heterocyclyl.In certain embodiments, at least one instance of R^(C) is unsaturatedheterocyclyl. In certain embodiments, at least one instance of R^(C) isheterocyclyl, wherein one, two, or three atoms in the heterocyclic ringsystem are independently selected from the group consisting of nitrogen,oxygen, and sulfur. In certain embodiments, at least one instance ofR^(C) is monocyclic heterocyclyl. In certain embodiments, at least oneinstance of R^(C) is 3- to 7-membered, monocyclic heterocyclyl. Incertain embodiments, at least one instance of R^(C) is substituted aryl.In certain embodiments, at least one instance of R^(C) is unsubstitutedaryl. In certain embodiments, at least one instance of R^(C) is 6- to10-membered aryl. In certain embodiments, at least one instance of R^(C)is substituted phenyl. In certain embodiments, at least one instance ofR^(C) is unsubstituted phenyl. In certain embodiments, at least oneinstance of R^(C) is substituted heteroaryl. In certain embodiments, atleast one instance of R^(C) is unsubstituted heteroaryl. In certainembodiments, at least one instance of R^(C) is heteroaryl, wherein one,two, three, or four atoms in the heteroaryl ring system areindependently selected from the group consisting of nitrogen, oxygen,and sulfur. In certain embodiments, at least one instance of R^(C) ismonocyclic heteroaryl. In certain embodiments, at least one instance ofR^(C) is 5-membered, monocyclic heteroaryl. In certain embodiments, atleast one instance of R^(C) is 6-membered, monocyclic heteroaryl. Incertain embodiments, at least one instance of R^(C) is bicyclicheteroaryl, wherein the point of attachment may be on any atom of thebicyclic heteroaryl ring system, as valency permits. In certainembodiments, at least one instance of R^(C) is 9- or 10-membered,bicyclic heteroaryl. In certain embodiments, at least one instance ofR^(C) is —OR^(a). In certain embodiments, at least one instance of R^(C)is —OH. In certain embodiments, at least one instance of R^(C) is—O(substituted or unsubstituted C₁₋₆ alkyl). In certain embodiments, atleast one instance of R^(C) is —OMe. In certain embodiments, at leastone instance of R^(C) is —OEt, —OPr, or —OBu. In certain embodiments, atleast one instance of R^(C) is —OBn or —OPh. In certain embodiments, atleast one instance of R^(C) is —SR^(a). In certain embodiments, at leastone instance of R^(C) is —SH. In certain embodiments, at least oneinstance of R^(C) is —SMe. In certain embodiments, at least one instanceof R^(C) is —N(R^(a))₂. In certain embodiments, at least one instance ofR^(C) is —NH₂. In certain embodiments, at least one instance of R^(C) is—NHMe. In certain embodiments, at least one instance of R^(C) is —NMe₂.In certain embodiments, at least one instance of R^(C) is —CN. Incertain embodiments, at least one instance of R^(C) is —SCN. In certainembodiments, at least one instance of R^(C) is —C(═NR^(a))R^(a),—C(═NR^(a))OR^(a), or —C(═NR^(a))N(R^(a))₂. In certain embodiments, atleast one instance of R^(C) is —C(═O)R″ or —C(═O)OR^(a). In certainembodiments, at least one instance of R^(C) is —C(═O)N(R^(a))₂. Incertain embodiments, at least one instance of R^(C) is —C(═O)NMe₂,—C(═O)NHMe, or —C(═O)NH₂. In certain embodiments, at least one instanceof R^(C) is —NO₂. In certain embodiments, at least one instance of R^(C)is —NR^(a)C(═O)R^(a), —NR^(a)C(═O)OR^(a), or —NR^(a)C(═O)N(R^(a))₂. Incertain embodiments, at least one instance of R^(C) is —OC(═O)R^(a),—OC(═O)OR^(a), or —OC(═O)N(R^(a))₂.

In certain embodiments, n is 0. In certain embodiments, n is 1. Incertain embodiments, n is 2. In certain embodiments, n is 3. In certainembodiments, n is 4.

In certain embodiments, at least one instance of R^(B) and at least oneinstance of R^(C) are different from each other. In certain embodiments,the instance of R^(B) at the carbon atom labeled with w′ is the same asthe instance of R^(C) at the carbon atom labeled with w″, wherein w is2, 3, 4, 5, or 6. In certain embodiments, m and n are different fromeach other. In certain embodiments, m and n are the same. In certainembodiments, each of m and n is 0.

Formula (A) includes a divalent linker Z^(A) that directly covalentlyconnects Ring A and Ring B. In certain embodiments, Z^(A) is a bond. Incertain embodiments, Z^(A) is a substituted or unsubstituted C₁₋₄hydrocarbon chain, optionally wherein one or more chain atoms areindependently replaced with —O—, —S—, —NR^(ZA)—, —N═, or ═N—. In certainembodiments, when Z^(A) is a substituted or unsubstituted C₁₋₆hydrocarbon chain, Z^(A) consists of a chain, and optionally one or morehydrogen atoms and/or one or more substituents (e.g., ═O) on the chain,where any two substituents may optionally be joined to form a ring. Incertain embodiments, Z^(A) does not include unsaturated bonds in thechain. In certain embodiments, Z^(A) consists of one or two unsaturatedbonds in the chain. In certain embodiments, Z^(A) is a substituted(e.g., substituted with at least one instance of halogen) C₁₋₆hydrocarbon chain. In certain embodiments, Z^(A) is an unsubstitutedC₁₋₄ hydrocarbon chain. In certain embodiments, the molecular weight ofZ^(A) is not more than about 150 g/mol, not more than about 100 g/mol,not more than 80 g/mol, not more than about 50 g/mol, or not more thanabout 30 g/mol. In certain embodiments, Z^(A) consists of not more thanabout 50 atoms, not more than about 40 atoms, not more than about 30atoms, not more than about 20 atoms, or not more than about 10 atoms. Incertain embodiments, Z^(A) is —C≡C— or —C≡C—C≡C—. In certainembodiments, Z^(A) is of the formula:

In certain embodiments, all instances of R^(ZA) are the same. In certainembodiments, at least two instances of R^(A2) are different from eachother. In certain embodiments, at least one instance of R^(ZA) ishydrogen. In certain embodiments, all instances of R^(ZA) are hydrogen.In certain embodiments, at least one instance of R^(ZA) is substitutedor unsubstituted C₁₋₆ alkyl (e.g., —CH₃, —CF₃, unsubstituted ethyl,perfluoroethyl, unsubstituted propyl, perfluoropropyl, unsubstitutedbutyl, or perfluorobutyl). In certain embodiments, at least one instanceof R^(ZA) is a nitrogen protecting group (e.g., Bn, Boc, Cbz, Fmoc,trifluoroacetyl, triphenylmethyl, acetyl, or Ts).

In certain embodiments, Z^(A) is directly covalently attached to thecarbon atom labeled with 2′ or 6′ of Ring B. In certain embodiments,Z^(A) is directly covalently attached to the carbon atom labeled with 3′or 5′ of Ring B. In certain embodiments, Z^(A) is directly covalentlyattached to the carbon atom labeled with 4′ of Ring B.

Formula (A) includes a divalent linker Z^(B) that directly covalentlyconnects Ring A and Ring C. In certain embodiments, Z^(B) is a bond. Incertain embodiments, Z^(B) is a substituted or unsubstituted C₁₋₄hydrocarbon chain, optionally wherein one or more chain atoms areindependently replaced with —O—, —S—, —NR^(ZB)—, —N═, or ═N—. In certainembodiments, when Z^(B) is a substituted or unsubstituted C₁₋₄hydrocarbon chain, Z^(B) consists of a chain, and optionally one or morehydrogen atoms and/or one or more substituents (e.g., ═O) on the chain,where any two substituents may optionally be joined to form a ring. Incertain embodiments, Z^(B) does not include unsaturated bonds in thechain. In certain embodiments, Z^(B) consists of one or two unsaturatedbonds in the chain. In certain embodiments, Z^(B) is a substituted(e.g., substituted with at least one instance of halogen) C₁₋₆hydrocarbon chain. In certain embodiments, Z^(B) is an unsubstitutedC₁₋₄ hydrocarbon chain. In certain embodiments, the molecular weight ofZ^(B) is not more than about 150 g/mol, not more than about 100 g/mol,not more than 80 g/mol, not more than about 50 g/mol, or not more thanabout 30 g/mol. In certain embodiments, Z^(B) consists of not more thanabout 50 atoms, not more than about 40 atoms, not more than about 30atoms, not more than about 20 atoms, or not more than about 10 atoms. Incertain embodiments, Z^(B) is —C≡C— or —C≡C—C≡C—. In certainembodiments, Z^(B) is of the formula:

In certain embodiments, all instances of R^(ZB) are the same. In certainembodiments, at least two instances of R^(ZB) are different from eachother. In certain embodiments, at least one instance of R^(ZB) ishydrogen. In certain embodiments, all instances of R^(ZB) are hydrogen.In certain embodiments, at least one instance of R^(ZB) is substitutedor unsubstituted C₁₋₆ alkyl (e.g., —CH₃, —CF₃, unsubstituted ethyl,perfluoroethyl, unsubstituted propyl, perfluoropropyl, unsubstitutedbutyl, or perfluorobutyl). In certain embodiments, at least one instanceof R^(ZB) is a nitrogen protecting group (e.g., Bn, Boc, Cbz, Fmoc,trifluoroacetyl, triphenylmethyl, acetyl, or Ts).

In certain embodiments, Z^(B) is directly covalently attached to thecarbon atom labeled with 2 or 6 of Ring A. In certain embodiments, Z^(B)is directly covalently attached to the carbon atom labeled with 3 or 5of Ring A. In certain embodiments, Z^(B) is directly covalently attachedto the carbon atom labeled with 4 of Ring A.

In certain embodiments, Z^(B) is directly covalently attached to thecarbon atom labeled with 2″ or 6″ of Ring C. In certain embodiments,Z^(B) is directly covalently attached to the carbon atom labeled with 3″or 5″ of Ring C. In certain embodiments, Z^(B) is directly covalentlyattached to the carbon atom labeled with 4″ of Ring C.

In certain embodiments, Z^(A) and Z^(B) are different from each other.In certain embodiments, Z^(A) and Z^(B) are the same. In certainembodiments, each of Z^(A) and Z^(B) is a bond.

In certain embodiments, Z^(A) is directly covalently attached to thecarbon atom labeled with 2′ or 6′ of Ring B; and Z^(B) is directlycovalently attached to the carbon atom labeled with 2″ or 6″ of Ring C.In certain embodiments, Z^(A) is directly covalently attached to thecarbon atom labeled with 3′ or 5′ of Ring B; and Z^(B) is directlycovalently attached to the carbon atom labeled with 3″ or 5″ of Ring C.In certain embodiments, Z^(A) is directly covalently attached to thecarbon atom labeled with 4′ of Ring B; and Z^(B) is directly covalentlyattached to the carbon atom labeled with 4″ of Ring C.

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In certain embodiments, the ligand of Formula (A) is of the formula:

In a nanostructure described herein, each instance of the transitionmetal ion and two instances of the ligand of Formula (A) form throughcoordination bonds a coordination complex. In certain embodiments, eachinstance of the ligand of Formula (A) forms through coordination bonds acoordination complex with one instance of the transition metal ion. Incertain embodiments, an instance of the coordination bonds is formedbetween an instance of the transition metal ion and the nitrogen atomlabeled with 1′ of an instance of the ligand of Formula (A). In certainembodiments, an instance of the coordination bonds is formed between aninstance of the transition metal ion and the nitrogen atom labeled with1″ of an instance of the ligand of Formula (A). In certain embodiments,an instance of the coordination bonds is formed between an instance ofthe transition metal ion and the nitrogen atom labeled with 1′ of aninstance of the ligand of Formula (A), and another instance of thecoordination bonds is formed between the instance of the transitionmetal ion and the nitrogen atom labeled with 1″ of the instance of theligand of Formula (A).

In a nanostructure described herein, each instance of the coordinationcomplex may be in a square planar molecular geometry. In a nanostructuredescribed herein, each instance of the coordination complex may also bein a pseudo square planar molecular geometry.

A nanostructure described herein may be a nanosphere. In certainembodiments, the nanosphere has quasi-regular polyhedral symmetry. Incertain embodiments, the nanosphere has cuboctahedral symmetry. Incertain embodiments, the nanosphere has icosidodecahedral symmetry. Incertain embodiments, the nanosphere has regular polyhedral symmetry(e.g., cubic (regular hexahedral) or dodecahedral symmetry).

A nanostructure described herein may be a nano-paddlewheel.

A nanostructure described herein is hollow (e.g., including a cavity).In certain embodiments, the average (e.g., mean) outer diameter of ananostructure described herein is not more than about 100 nm, not morethan about 60 nm, not more than about 30 nm, not more than about 10 nm,not more than about 5 nm, not more than about 3 nm, or not more thanabout 1 nm. In certain embodiments, the average outer diameter of the ananostructure described herein is at least about 1 nm, at least about 2nm, at least about 5 nm, at least about 10 nm, at least about 30 nm, atleast about 60 nm, or at least about 100 nm. Combinations of the aboveranges (e.g., at least about 1 nm and not more than about 100 nm or atleast about 1 nm and not more than about 10 nm) are also within thescope of the present disclosure. The average inner diameter of ananostructure described herein is the average diameter of the cavity ofthe nanostructure. In certain embodiments, the average inner diameter ofa nanostructure described herein is not more than about 100 nm, not morethan about 60 nm, not more than about 30 nm, not more than about 10 nm,not more than about 5 nm, not more than about 3 nm, or not more thanabout 1 nm. In certain embodiments, the average inner diameter of thenanostructure described herein is at least about 1 nm, at least about 2nm, at least about 5 nm, at least about 10 nm, at least about 30 nm, atleast about 60 nm, or at least about 100 nm. Combinations of the aboveranges (e.g., at least about 1 nm and not more than about 60 nm or atleast about 1 nm and not more than about 5 nm) are also within the scopeof the present disclosure.

In certain embodiments, a nanostructure described herein is not apolymer or does not include a polymeric moiety.

In certain embodiments, a nanosphere described herein is of Formula(I-A), or a salt thereof.

In certain embodiments, a nanosphere described herein is of Formula(I-B), or a salt thereof.

In certain embodiments, a nanosphere described herein (nanosphere I-1)is of Formula (I-A), wherein each instance of the gray line is ligandA-1. In Formula (I-A), each instance of the moiety shown in FIG. 31 isof the formula:

In certain embodiments, each instance of the moiety shown in FIG. 31 isof the formula:

In certain embodiments, a nano-paddlewheel described herein is of theformula depicted in Scheme 8.

Supramolecular Complexes

Another aspect of the present disclosure relates to supramolecularcomplexes that include nanostructures described herein covalentlyconnected by divalent linkers Y. In certain embodiments, asupramolecular complex described herein includes two or more (e.g., atleast 10, at least 100, at least 1,000, or at least 10,000) instances ofa nanostructure described herein and at least one instance of Y.

Each instance of Y consists of a chain, and optionally one or morehydrogen atoms and/or one or more substituents (e.g., ═O, halogen, andsubstituted or unsubstituted C₁₋₆ alkyl) on the chain, wherein any twosubstituents may optionally be joined to form a ring. In certainembodiments, at least two instances of Y are different from each other.In certain embodiments, all instances of Y are the same. In certainembodiments, at least one instance of Y does not include unsaturatedbonds in the chain. In certain embodiments, at least one instance of Yconsists of one or more unsaturated bonds in the chain. In certainembodiments, at least one instance of Y is a substituted orunsubstituted C₃₀₋₃₀₀₀ (e.g., C₁₀₀₋₃₀₀₀, C₂₀₀₋₂₅₀₀, C₃₀₀₋₂₀₀₀,C₄₀₀₋₁₅₀₀, C₇₀₋₁₅₀₀, C₅₀₀₋₁₀₀₀, C₁₀₀₋₁₀₀₀, C₃₀₋₅₀₀, C₄₀₋₄₀₀, C₆₀₋₃₀₀, orC₈₀₋₂₀₀) hydrocarbon chain, optionally wherein one or more chain atomsare independently replaced with —O—, —S—, —NR^(Y)—, —N═, or ═N—. Incertain embodiments, at least one instance of Y is a substituted orunsubstituted C₈₀₋₁₀₀₀ hydrocarbon chain, optionally wherein one or morechain atoms are independently replaced with —O—, —S—, —NR^(Y)—, —N═, or═N—. In certain embodiments, each chain atom, with any substituentsthereon, of at least one instance of Y is independently —CH₂—,—CH(substituted or unsubstituted C₁₋₆ alkyl)-, —C(substituted orunsubstituted C₁₋₆ alkyl)₂-, —C(═O)—, —O—, —NH—, —N(substituted orunsubstituted C₁₋₆ alkyl)-, or —N(nitrogen protecting group)-. Incertain embodiments, each chain atom, with any substituents thereon, ofat least one instance of Y is independently —CH₂—, —CF₂—, —C(═O)—, —O—,—NH—, or —NMe—. In certain embodiments, each chain atom, with anysubstituents thereon, of at least one instance of Y is independently—CH₂—, —C(═O)—, or —O—. In certain embodiments, at least one instance ofY comprises at least one instance of the moiety —C(═O)O— or —OC(═O)—. Incertain embodiments, each instance of Y is independently of the formula:

In certain embodiments, each instance of Y is independently of theformula:

In certain embodiments, each instance of Y is independently of theformula:

In certain embodiments, each instance of Y is independently of theformula:

In certain embodiments, each instance of Y is independently of theformula:

In certain embodiments, each instance of Y is independently of theformula:

In certain embodiments, each instance of Y is independently of theformula:

In certain embodiments, the molecular weight of at least one instance ofY (calculated by subtracting 2 from the molecular weight of the moleculeYH₂) is not more than about 100,000 g/mol, not more than about 30,000g/mol, not more than 10,000 g/mol, not more than about 3,000 g/mol, notmore than about 1,000 g/mol, not more than about 300 g/mol, or not morethan about 100 g/mol. In certain embodiments, the molecular weight of atleast one instance of Y is at least about 100 g/mol, at least about 300g/mol, at least about 1,000 g/mol, at least about 3,000 g/mol, at leastabout 10,000 g/mol, at least about 30,000 g/mol, or at least about100,000 g/mol. Combinations of the above ranges (e.g., between about 300and about 30,000 g/mol) are also within the scope of the presentdisclosure. In certain embodiments, at least one instance of Y consistsof not more than about 30,000 atoms, not more than about 10,000 atoms,not more than about 3,000 atoms, not more than about 1,000 atoms, notmore than about 300 atoms, not more than about 100 atoms, or not morethan about 30 atoms. In certain embodiments, at least one instance of Yconsists of at least about 30 atoms, at least about 100 atoms, at leastabout 300 atoms, at least about 1,000 atoms, at least about 3,000 atoms,at least about 10,000 atoms, or at least about 30,000 atoms.Combinations of the above ranges (e.g., between about 30 and about10,000 g/mol) are also within the scope of the present disclosure.

In certain embodiments, at least one instance of Y is hydrolyticallyunstable under physiological conditions. In certain embodiments, atleast one instance of Y includes a hydrolytically unstable moiety (e.g.,—C(═O)O— or —C(═O)O—) in the chain of Y. In certain embodiments, atleast one instance of Y is hydrolytically stable under physiologicalconditions.

In certain embodiments, all instances of R^(Y) are the same. In certainembodiments, at least two instances of R^(Y) are different from eachother. In certain embodiments, at least one instance of R^(Y) ishydrogen. In certain embodiments, all instances of R^(Y) are hydrogen.In certain embodiments, at least one instance of R^(Y) is substituted orunsubstituted C₁₋₆ alkyl (e.g., —CH₃, —CF₃, unsubstituted ethyl,perfluoroethyl, unsubstituted propyl, perfluoropropyl, unsubstitutedbutyl, or perfluorobutyl). In certain embodiments, at least one instanceof R^(Y) is a nitrogen protecting group (e.g., Bn, Boc, Cbz, Fmoc,trifluoroacetyl, triphenylmethyl, acetyl, or Ts).

An instance of Y may be directly covalently attached to an instance ofthe ligand of Formula (A) (e.g., by removing a hydrogen atom from theinstance of the ligand of Formula (A) to form a radical (ligand radical)and directly covalently attaching one of the two radicals of theinstance of Y to the ligand radical). Each instance of Y isindependently directly covalently attached to an instance of the ligandof Formula (A) and directly covalently attached to another instance ofthe ligand of Formula (A). In certain embodiments, each instance of theligand of Formula (A) is covalently attached to w instances of Y,wherein w is 1. In certain embodiments, each instance of the ligand ofFormula (A) is covalently attached to w instances of Y, wherein w is 2.In certain embodiments, at least one instance of Y is directlycovalently attached to the atom labeled with 2, 3, 4, 5, or 6 (e.g., 3,4, or 5) of an instance of the ligand of Formula (A) and directlycovalently attached to the atom labeled with 2, 3, 4, 5, or 6 (e.g., 3,4, or 5) of another instance of the ligand of Formula (A). In certainembodiments, at least one instance of Y is directly covalently attachedto the atom labeled with 2′, 3′, 4′, 5′, or 6′ (e.g., 3′, 4′, or 5′) ofan instance of the ligand of Formula (A) and directly covalentlyattached to the atom labeled with 2′, 3′, 4′, 5′, or 6′ (e.g., 3′, 4′,or 5′) of another instance of the ligand of Formula (A). In certainembodiments, at least one instance of Y is directly covalently attachedto the atom labeled with 2″, 3″, 4″, 5″, or 6″ (e.g., 3″, 4″, or 5″) ofan instance of the ligand of Formula (A) and directly covalentlyattached to the atom labeled with 2″, 3″, 4″, 5″, or 6″ (e.g., 3″, 4″,or 5″) of another instance of the ligand of Formula (A). In asupramolecular complex described herein, at least two instances of thenanostructure are directly covalently connected by at least one instanceof Y. In certain embodiments, at least about 50% (e.g., at least about60%, at least about 70%, at least about 80%, or at least about 90%) ofall instances of Y directly covalently attached to an instance of thenanostructure are directly covalently attached to other instances of thenanostructure.

A nanostructure or supramolecular complex described herein may furthercomprise at least one instance of an anionic counterion. The anioniccounterions may reduce the overall electric charge of the nanostructureor supramolecular complex, each of which includes transition metal ionsthat are positively charged. In certain embodiments, at least twoinstances of the anionic counterion are different. In certainembodiments, all instances of the anionic counterion are the same. Incertain embodiments, the nanostructure or supramolecular complex issubstantially electrically neutral. In certain embodiments, thenanostructure or supramolecular complex is slightly positively charged.In certain embodiments, the C-potential of the nanostructure orsupramolecular complex is between about 0 and about +30 mV, inclusive(e.g., between about 0 and about 10 mV, inclusive). In certainembodiments, the nanostructure or supramolecular complex is slightlynegatively charged. In certain embodiments, the ζ-potential of thenanostructure or supramolecular complex is between about −30 and about 0mV, inclusive (e.g., between about −10 and about 0 mV, inclusive). Incertain embodiments, at least one instance of the anionic counterion isa non-coordinating anionic counterion (e.g., ClO₄ ⁻, NO₃ ⁻, TfO⁻, BF₄ ⁻,PF₄ ⁻, PF₆ ⁻, AsF₆ ⁻, or SbF₆ ⁻). In certain embodiments, at least oneinstance (e.g., each instance) of the anionic counterion is NO₃ ⁻. Incertain embodiments, at least one instance of the anionic counterion isAcO⁻, F⁻, Cr⁻, Br⁻, or I⁻. In certain embodiments, at least one instanceof the anionic counterion is a coordinating anionic counterion. Incertain embodiments, at least one instance (e.g., each instance) of theanionic counterion is at the outer surface of an instance of thenanostructure. In certain embodiments, at least one instance of theanionic counterion is at the inner surface of an instance of thenanostructure. In certain embodiments, at least one instance of theanionic counterion is encapsulated by an instance of the nanostructure.

Macromers

In another aspect, the present disclosure provides macromers of Formula(B), and salts thereof:

wherein Ring A, X^(A), X^(B), X^(C), X^(D), X^(E), Y, Z^(A), Z^(B),R^(B), R^(C), m, and n are as described herein.

In certain embodiments, the macromer of Formula (B) is of the formula:

or a salt thereof, wherein each instance of X^(D) is N or C.

In certain embodiments, the macromer of Formula (B) is of the formula:

or a salt thereof.

In certain embodiments, the macromer of Formula (B) is of the formula:

or a salt thereof.

In certain embodiments, the macromer of Formula (B) is of the formula:

or a salt thereof.

In certain embodiments, the macromer of Formula (B) is of the formula:

or a salt thereof.

In certain embodiments, the macromer of Formula (B) is of Formula (B-1),(B-2), or (B-3):

or a salt thereof.

In another aspect, the present disclosure provides macromers of Formula(C), and salts thereof:

wherein Ring A, X^(A), X^(B), X^(C), X^(D), X^(E), Y, Z^(A), Z^(B),R^(B), R^(C), m, and n are as described herein.

In certain embodiments, the macromer of Formula (C) is of the formula:

or a salt thereof.

In certain embodiments, the macromer of Formula (C) is of the formula:

or a salt thereof.

In certain embodiments, the macromer of Formula (C) is of the formula:

or a salt thereof.Compositions

In another aspect, the present disclosure provides compositionscomprising a nanostructure described herein and optionally an excipient.A composition described herein may further comprise a solvent (e.g., asuitable solvent described herein, such as water or DMSO). The solventmay be encapsulated inside a nanostructure and/or be present outside ofany nanostructure in the composition.

In still another aspect, the present disclosure provides compositionscomprising a supramolecular complex described herein and optionally anexcipient.

The excipient included in a composition described herein may be apharmaceutically acceptable excipient, cosmetically acceptableexcipient, dietarily acceptable excipient, or nutraceutically acceptableexcipient.

A composition described herein may further comprise an agent (e.g., apharmaceutical agent or diagnostic agent). In a composition describedherein, an agent may form an adduct (e.g., through covalent attachmentand/or non-covalent interactions) with a nanostructure described herein(including a nanostructure moiety of a supramolecular complex describedherein). In certain embodiments, a composition described herein isuseful in the delivery of the agent (e.g., an effective amount of theagent) to a subject, tissue, or cell.

A composition described herein may further comprise a fluid (e.g., asolvent, e.g., water, DMSO, acetonitrile, or a mixture thereof)

Compositions of the disclosure may improve or increase the delivery ofan agent described herein to a subject, tissue, or cell. In certainembodiments, the compositions increase the delivery of the agent to atarget tissue or target cell. In certain embodiments, the target tissueis liver, spleen, or lung. In certain embodiments, the target tissue ispancreas, kidney, uterus, ovary, heart, thymus, fat, or muscle. Incertain embodiments, the target cell is a liver cell, spleen cell, lungcell, pancreas cell, kidney cell, uterus cell, ovary cell, heart cell,thymus cell, or muscle cell. In certain embodiments, the compositionsselectively deliver the agent to the target tissue or target cell (e.g.,the compositions deliver the agent to the target tissue in a greaterquantity in unit time than to a non-target tissue or deliver the agentto the target cell in a greater quantity in unit time than to anon-target cell).

The delivery of an agent described herein may be characterized invarious ways, such as the exposure, concentration, and bioavailabilityof the agent. The exposure of an agent in a subject, tissue, or cell maybe defined as the area under the curve (AUC) of the concentration of theagent in the subject, tissue, or cell after administering or dosing theagent. In general, an increase in exposure may be calculated by firsttaking the difference in: (1) a first AUC, which is the AUC measured ina subject, tissue, or cell administered or dosed with a compositiondescribed herein; and (2) a second AUC, which is the AUC measured in asubject, tissue, or cell administered or dosed with a controlcomposition; and then by dividing the difference by the second AUC.Exposure of an agent may be measured in an appropriate animal model. Theconcentration of an agent and, when appropriate, its metabolite(s), in asubject, tissue, or cell is measured as a function of time afteradministering or dosing the agent.

Concentration of an agent, and, when appropriate, of its metabolite(s),in a subject, tissue, or cell, may be measured as a function of time invivo using an appropriate animal model. In certain embodiments, theconcentration of the agent is the concentration of the agent in a targettissue or target cell. One exemplary method of determining theconcentration of an agent involves dissecting of a tissue. Theconcentration of the agent may be determined by HPLC or LC/MS analysis.

In some embodiments, a composition of the disclosure increases thedelivery of an agent described herein to a subject, tissue, or cell bydue to the presence of a nanostructure described herein. In someembodiments, a composition of the disclosure increases the delivery ofan agent described herein to a subject, tissue, or cell by due to thepresence of a supramolecular complex described herein. In someembodiments, the composition increases the delivery of the agent due tothe presence of an adduct formed between the nanostructure (including ananostructure moiety of a supramolecular complex) and the agent. In someembodiments, the presence of a nanostructure or supramolecular complexdescribed herein increase the delivery of the agent by at least about10%, at least about 20%, at least about 30%, at least about 40%, atleast about 50%, at least about 100%, at least about 2-fold, at leastabout 3-fold, at least about 10-fold, at least about 30-fold, at leastabout 100-fold, at least about 300-fold, or at least about 1000-fold. Incertain embodiments, a nanostructure or supramolecular complex describedherein is present in the composition in an amount sufficient to increasethe delivery of the agent by an amount described herein whenadministered in the composition compared to the delivery of the agentwhen administered in the absence of the nanostructure or supramolecularcomplex.

Compositions described herein may deliver an agent selectively to atissue or cell. In certain embodiments, the tissue or cell to which theagent is selectively delivered is a target tissue or target cell,respectively. In certain embodiments, the compositions deliver at leastabout 10%, at least about 20%, at least about 30%, at least about 40%,at least about 50%, at least about 70%/o, at least about 100%, at leastabout 3-fold, at least about 10-fold, at least about 30-fold, at leastabout 100-fold, at least about 300-fold, or at least about 1000-foldmore amount of the agent in unit time to a target tissue than to anon-target tissue or to a target cell than to a non-target cell. Theamount of agent may be measured by the exposure, concentration, and/orbioavailability of the agent in a tissue or cell as described herein.

The compositions described herein (e.g., pharmaceutical compositions)including one or more agents (e.g., pharmaceutical agents) may be usefulin treating and/or preventing a disease. In certain embodiments, thecompositions are useful in gene therapy. In certain embodiments, thecompositions are useful for treating and/or preventing a geneticdisease. In certain embodiments, the compositions are useful fortreating and/or preventing a proliferative disease. In certainembodiments, the compositions are useful for treating and/or preventingcancer. In certain embodiments, the compositions are useful for treatingand/or preventing a benign neoplasm. In certain embodiments, thecompositions are useful for treating and/or preventing pathologicalangiogenesis. In certain embodiments, the compositions are useful fortreating and/or preventing an inflammatory disease. In certainembodiments, the compositions are useful for treating and/or preventingan autoimmune disease. In certain embodiments, the compositions areuseful for treating and/or preventing a hematological disease. Incertain embodiments, the compositions are useful for treating and/orpreventing a neurological disease. In certain embodiments, thecompositions are useful for treating and/or preventing agastrointestinal disease. In certain embodiments, the compositions areuseful for treating and/or preventing a liver disease. In certainembodiments, the compositions are useful for treating and/or preventinga spleen disease. In certain embodiments, the compositions are usefulfor treating and/or preventing a respiratory disease. In certainembodiments, the compositions are useful for treating and/or preventinga lung disease. In certain embodiments, the compositions are useful fortreating and/or preventing hepatic carcinoma, hypercholesterolemia,refractory anemia, or familial amyloid neuropathy. In certainembodiments, the compositions are useful for treating and/or preventinga painful condition. In certain embodiments, the compositions are usefulfor treating and/or preventing a genitourinary disease. In certainembodiments, the compositions are useful for treating and/or preventinga musculoskeletal condition. In certain embodiments, the compositionsare useful for treating and/or preventing an infectious disease. Incertain embodiments, the compositions are useful for treating and/orpreventing a psychiatric disorder. In certain embodiments, thecompositions are useful for treating and/or preventing a metabolicdisorder.

The agents may be provided in an effective amount in a compositiondescribed herein. In certain embodiments, the effective amount is atherapeutically effective amount. In certain embodiments, the effectiveamount is a prophylactically effective amount. In certain embodiments,the effective amount is an amount effective for treating a diseasedescribed herein. In certain embodiments, the effective amount is anamount effective for preventing a disease described herein.

An effective amount of an agent may vary from about 0.001 mg/kg to about1000 mg/kg in one or more dose administrations for one or several days(depending on the mode of administration). In certain embodiments, theeffective amount per dose varies from about 0.001 to about 1000 mg/kg,from about 0.01 to about 750 mg/kg, from about 0.1 to about 500 mg/kg,from about 1.0 to about 250 mg/kg, and from about 10.0 to about 150mg/kg.

In certain embodiments, a composition described herein is in the form ofgels. In certain embodiments, the gels result from self-assembly of thecomponents of the composition. The agent to be delivered by the gel maybe in the form of a gas, liquid, or solid. The nanostructures and/orsupramolecular complexes described herein may be combined with polymers(synthetic or natural), surfactants, cholesterol, carbohydrates,proteins, lipids, lipidoids, etc. to form gels. The gels may be furthercombined with an excipient to form the composition. The gels aredescribed in more detail herein.

The compositions described herein (e.g., pharmaceutical compositions)can be prepared by any method known in the art (e.g., pharmacology). Incertain embodiments, such preparatory methods include the steps ofbringing a nanostructure or supramolecular complex described herein intoassociation with an agent described herein (i.e., the “activeingredient”), optionally with a carrier or excipient, and/or one or moreother accessory ingredients, and then, if necessary and/or desirable,shaping, and/or packaging the product into a desired single- ormulti-dose unit.

Compositions can be prepared, packaged, and/or sold in bulk, as a singleunit dose, and/or as a plurality of single unit doses. A unit dose is adiscrete amount of the composition comprising a predetermined amount ofthe active ingredient. The amount of the active ingredient is generallyequal to the dosage of the active ingredient which would be administeredto a subject and/or a convenient fraction of such a dosage such as, forexample, one-half or one-third of such a dosage.

Relative amounts of the active ingredient, the excipient (e.g., thepharmaceutically or cosmetically acceptable excipient), and/or anyadditional ingredients in a composition described herein will vary,depending upon the identity, size, and/or condition of the subject towhom the composition is administered and further depending upon theroute by which the composition is to be administered. The compositionmay comprise between 0.1% and 100% (w/w) active ingredient.

Excipients used in the manufacture of provided compositions includeinert diluents, dispersing and/or granulating agents, surface activeagents and/or emulsifiers, disintegrating agents, binding agents,preservatives, buffering agents, lubricating agents, and/or oils.Excipients such as cocoa butter and suppository waxes, coloring agents,coating agents, sweetening, flavoring, and perfuming agents may also bepresent in the composition.

Exemplary diluents include calcium carbonate, sodium carbonate, calciumphosphate, dicalcium phosphate, calcium sulfate, calcium hydrogenphosphate, sodium phosphate lactose, sucrose, cellulose,microcrystalline cellulose, kaolin, mannitol, sorbitol, inositol, sodiumchloride, dry starch, cornstarch, powdered sugar, and mixtures thereof.

Exemplary granulating and/or dispersing agents include potato starch,corn starch, tapioca starch, sodium starch glycolate, clays, alginicacid, guar gum, citrus pulp, agar, bentonite, cellulose, and woodproducts, natural sponge, cation-exchange resins, calcium carbonate,silicates, sodium carbonate, cross-linked poly(vinyl-pyrrolidone)(crospovidone), sodium carboxymethyl starch (sodium starch glycolate),carboxymethyl cellulose, cross-linked sodium carboxymethyl cellulose(croscarmellose), methylcellulose, pregelatinized starch (starch 1500),microcrystalline starch, water insoluble starch, calcium carboxymethylcellulose, magnesium aluminum silicate (Veegum), sodium lauryl sulfate,quaternary ammonium compounds, and mixtures thereof.

Exemplary surface active agents and/or emulsifiers include naturalemulsifiers (e.g., acacia, agar, alginic acid, sodium alginate,tragacanth, chondrux, cholesterol, xanthan, pectin, gelatin, egg yolk,casein, wool fat, cholesterol, wax, and lecithin), colloidal clays(e.g., bentonite (aluminum silicate) and Veegum (magnesium aluminumsilicate)), long chain amino acid derivatives, high molecular weightalcohols (e.g., stearyl alcohol, cetyl alcohol, oleyl alcohol, triacetinmonostearate, ethylene glycol distearate, glyceryl monostearate, andpropylene glycol monostearate, polyvinyl alcohol), carbomers (e.g.,carboxy polymethylene, polyacrylic acid, acrylic acid polymer, andcarboxyvinyl polymer), carrageenan, cellulosic derivatives (e.g.,carboxymethylcellulose sodium, powdered cellulose, hydroxymethylcellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose,methylcellulose), sorbitan fatty acid esters (e.g., polyoxyethylenesorbitan monolaurate (Tween® 20), polyoxyethylene sorbitan (Tween® 60),polyoxyethylene sorbitan monooleate (Tween® 80), sorbitan monopalmitate(Span® 40), sorbitan monostearate (Span® 60), sorbitan tristearate(Span® 65), glyceryl monooleate, sorbitan monooleate (Span® 80),polyoxyethylene esters (e.g., polyoxyethylene monostearate (Myrj® 45),polyoxyethylene hydrogenated castor oil, polyethoxylated castor oil,polyoxymethylene stearate, and Solutol®), sucrose fatty acid esters,polyethylene glycol fatty acid esters (e.g., Cremophor®),polyoxyethylene ethers, (e.g., polyoxyethylene lauryl ether (Brij® 30)),poly(vinyl-pyrrolidone), diethylene glycol monolaurate, triethanolamineoleate, sodium oleate, potassium oleate, ethyl oleate, oleic acid, ethyllaurate, sodium lauryl sulfate, Pluronic® F-68, Poloxamer P-188,cetrimonium bromide, cetylpyridinium chloride, benzalkonium chloride,docusate sodium, and mixtures thereof.

Exemplary binding agents include starch (e.g., cornstarch and starchpaste), gelatin, sugars (e.g., sucrose, glucose, dextrose, dextrin,molasses, lactose, lactitol, mannitol, etc.), natural and synthetic gums(e.g., acacia, sodium alginate, extract of Irish moss, panwar gum,ghatti gum, mucilage of isapol husks, carboxymethylcellulose,methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropyl methylcellulose, microcrystalline cellulose,cellulose acetate, poly(vinyl-pyrrolidone), magnesium aluminum silicate(Veegum®), and larch arabogalactan), alginates, polyethylene oxide,polyethylene glycol, inorganic calcium salts, silicic acid,polymethacrylates, waxes, water, alcohol, and mixtures thereof.

Exemplary preservatives include antioxidants, chelating agents,antimicrobial preservatives, antifungal preservatives, antiprotozoanpreservatives, alcohol preservatives, acidic preservatives, and otherpreservatives. In certain embodiments, the preservative is anantioxidant. In other embodiments, the preservative is a chelatingagent.

Exemplary antioxidants include alpha tocopherol, ascorbic acid, acorbylpalmitate, butylated hydroxyanisole, butylated hydroxytoluene,monothioglycerol, potassium metabisulfite, propionic acid, propylgallate, sodium ascorbate, sodium bisulfite, sodium metabisulfite,sodium sulfite, and mixtures thereof.

Exemplary chelating agents include ethylenediaminetetraacetic acid(EDTA) and salts and hydrates thereof (e.g., sodium edetate, disodiumedetate, trisodium edetate, calcium disodium edetate, and dipotassiumedetateke), citric acid and salts and hydrates thereof (e.g., citricacid monohydrate), fumaric acid and salts and hydrates thereof, malicacid and salts and hydrates thereof, phosphoric acid and salts andhydrates thereof, tartaric acid and salts and hydrates thereof, andmixtures thereof.

Exemplary antimicrobial preservatives include benzalkonium chloride,benzethonium chloride, benzyl alcohol, bronopol, cetrimide,cetylpyridinium chloride, chlorhexidine, chlorobutanol, chlorocresol,chloroxylenol, cresol, ethyl alcohol, glycerin, hexetidine, imidurea,phenol, phenoxyethanol, phenylethyl alcohol, phenylmercuric nitrate,propylene glycol, thimerosal, and mixtures thereof.

Exemplary antifungal preservatives include butyl paraben, methylparaben, ethyl paraben, propyl paraben, benzoic acid, hydroxybenzoicacid, potassium benzoate, potassium sorbate, sodium benzoate, sodiumpropionate, sorbic acid, and mixtures thereof.

Exemplary alcohol preservatives include ethanol, polyethylene glycol,phenol, phenolic compounds, bisphenol, chlorobutanol, hydroxybenzoate,phenylethyl alcohol, and mixtures thereof.

Exemplary acidic preservatives include vitamin A, vitamin C, vitamin E,beta-carotene, citric acid, acetic acid, dehydroacetic acid, ascorbicacid, sorbic acid, phytic acid, and mixtures thereof.

Other preservatives include tocopherol, tocopherol acetate, deteroximemesylate, cetrimide, butylated hydroxyanisol (BHA), butylatedhydroxytoluened (BHT), ethylenediamine, sodium lauryl sulfate (SLS),sodium lauryl ether sulfate (SLES), sodium bisulfite, sodiummetabisulfite, potassium sulfite, potassium metabisulfite, Glydant Plus,Phenonip®, methylparaben, Germall® 115, Germaben® II, Neolone®, Kathon®,Euxyl®, and mixtures thereof.

Exemplary buffering agents include citrate buffer solutions, acetatebuffer solutions, phosphate buffer solutions, ammonium chloride, calciumcarbonate, calcium chloride, calcium citrate, calcium glubionate,calcium gluceptate, calcium gluconate, D-gluconic acid, calciumglycerophosphate, calcium lactate, propanoic acid, calcium levulinate,pentanoic acid, dibasic calcium phosphate, phosphoric acid, tribasiccalcium phosphate, calcium hydroxide phosphate, potassium acetate,potassium chloride, potassium gluconate, potassium mixtures, dibasicpotassium phosphate, monobasic potassium phosphate, potassium phosphatemixtures, sodium acetate, sodium bicarbonate, sodium chloride, sodiumcitrate, sodium lactate, dibasic sodium phosphate, monobasic sodiumphosphate, sodium phosphate mixtures, tromethamine, magnesium hydroxide,aluminum hydroxide, alginic acid, pyrogen-free water, isotonic saline,Ringer's solution, ethyl alcohol, and mixtures thereof.

Exemplary lubricating agents include magnesium stearate, calciumstearate, stearic acid, silica, talc, malt, glyceryl behanate,hydrogenated vegetable oils, polyethylene glycol, sodium benzoate,sodium acetate, sodium chloride, leucine, magnesium lauryl sulfate,sodium lauryl sulfate, and mixtures thereof.

Exemplary natural oils include almond, apricot kernel, avocado, babassu,bergamot, black current seed, borage, cade, camomile, canola, caraway,carnauba, castor, cinnamon, cocoa butter, coconut, cod liver, coffee,corn, cotton seed, emu, eucalyptus, evening primrose, fish, flaxseed,geraniol, gourd, grape seed, hazel nut, hyssop, isopropyl myristate,jojoba, kukui nut, lavandin, lavender, lemon, litsea cubeba, macademianut, mallow, mango seed, meadowfoam seed, mink, nutmeg, olive, orange,orange roughy, palm, palm kernel, peach kernel, peanut, poppy seed,pumpkin seed, rapeseed, rice bran, rosemary, safflower, sandalwood,sasquana, savoury, sea buckthorn, sesame, shea butter, silicone,soybean, sunflower, tea tree, thistle, tsubaki, vetiver, walnut, andwheat germ oils. Exemplary synthetic oils include, but are not limitedto, butyl stearate, caprylic triglyceride, capric triglyceride,cyclomethicone, diethyl sebacate, dimethicone 360, isopropyl myristate,mineral oil, octyldodecanol, oleyl alcohol, silicone oil, and mixturesthereof.

Additionally, the composition may further comprise an apolipoprotein.Previous studies have reported that Apolipoprotein E (ApoE) was able toenhance cell uptake and gene silencing for a certain type of materials.See, e.g., Akinc, A., et al., Targeted delivery of RNAi therapeuticswith endogenous and exogenous ligand-based mechanisms. Mol Ther. 18(7):p. 1357-64. In certain embodiments, the apolipoprotein is ApoA, ApoB,ApoC, ApoE, or ApoH, or an isoform thereof.

Liquid dosage forms for oral and parenteral administration includeemulsions, microemulsions, solutions, suspensions, syrups and elixirs.In certain embodiments, the emulsions, microemulsions, solutions,suspensions, syrups and elixirs are or cosmetically acceptableemulsions, microemulsions, solutions, suspensions, syrups and elixirs.In addition to the active ingredients, the liquid dosage forms maycomprise inert diluents commonly used in the art such as, for example,water or other solvents, solubilizing agents and emulsifiers such asethyl alcohol, isopropyl alcohol, ethyl carbonate, ethyl acetate, benzylalcohol, benzyl benzoate, propylene glycol, 1,3-butylene glycol,dimethylformamide, oils (e.g., cottonseed, groundnut, corn, germ, olive,castor, and sesame oils), glycerol, tetrahydrofurfuryl alcohol,polyethylene glycols and fatty acid esters of sorbitan, and mixturesthereof. Besides inert diluents, the oral compositions can includeadjuvants such as wetting agents, emulsifying and suspending agents,sweetening, flavoring, and perfuming agents. In certain embodiments forparenteral administration, the conjugates described herein are mixedwith solubilizing agents such as Cremophore, alcohols, oils, modifiedoils, glycols, polysorbates, cyclodextrins, polymers, and mixturesthereof.

Injectable preparations, for example, sterile injectable aqueous oroleaginous suspensions can be formulated according to the known artusing suitable dispersing or wetting agents and suspending agents. Thesterile injectable preparation can be a sterile injectable solution,suspension, or emulsion in a nontoxic parenterally acceptable diluent orsolvent, for example, as a solution in 1,3-butanediol. Among theacceptable vehicles and solvents that can be employed are water,Ringer's solution, U.S.P., and isotonic sodium chloride solution. Inaddition, sterile, fixed oils are conventionally employed as a solventor suspending medium. For this purpose any bland fixed oil can beemployed including synthetic mono- or di-glycerides. In addition, fattyacids such as oleic acid are used in the preparation of injectables.

The injectable formulations can be sterilized, for example, byfiltration through a bacterial-retaining filter, or by incorporatingsterilizing agents in the form of sterile solid compositions which canbe dissolved or dispersed in sterile water or other sterile injectablemedium prior to use.

In order to prolong the effect of a drug, it is often desirable to slowthe absorption of the drug from subcutaneous or intramuscular injection.This can be accomplished by the use of a liquid suspension ofcrystalline or amorphous material with poor water solubility. The rateof absorption of the drug then depends upon its rate of dissolution,which, in turn, may depend upon crystal size and crystalline form.Alternatively, delayed absorption of a parenterally administered drugform may be accomplished by dissolving or suspending the drug in an oilvehicle.

Compositions for rectal or vaginal administration are typicallysuppositories which can be prepared by mixing the conjugates withsuitable non-irritating excipients or carriers such as cocoa butter,polyethylene glycol, or a suppository wax which are solid at ambienttemperature but liquid at body temperature and therefore melt in therectum or vaginal cavity and release the active ingredient.

Solid dosage forms for oral administration include capsules, tablets,pills, powders, and granules. In such solid dosage forms, the activeingredient is mixed with at least one inert, excipient or carrier (e.g.,pharmaceutically or cosmetically acceptable excipient or carrier) suchas sodium citrate or dicalcium phosphate and/or (a) fillers or extenderssuch as starches, lactose, sucrose, glucose, mannitol, and silicic acid,(b) binders such as, for example, carboxymethylcellulose, alginates,gelatin, polyvinylpyrrolidinone, sucrose, and acacia, (c) humectantssuch as glycerol, (d) disintegrating agents such as agar, calciumcarbonate, potato or tapioca starch, alginic acid, certain silicates,and sodium carbonate, (e) solution retarding agents such as paraffin,(f) absorption accelerators such as quaternary ammonium compounds, (g)wetting agents such as, for example, cetyl alcohol and glycerolmonostearate, (h) absorbents such as kaolin and bentonite clay, and (i)lubricants such as talc, calcium stearate, magnesium stearate, solidpolyethylene glycols, sodium lauryl sulfate, and mixtures thereof. Inthe case of capsules, tablets, and pills, the dosage form may include abuffering agent.

Solid compositions of a similar type can be employed as fillers in softand hard-filled gelatin capsules using such excipients as lactose ormilk sugar as well as high molecular weight polyethylene glycols and thelike. The solid dosage forms of tablets, dragees, capsules, pills, andgranules can be prepared with coatings and shells such as entericcoatings and other coatings well known in the art of pharmacology. Theymay optionally comprise opacifying agents and can be of a compositionthat they release the active ingredient(s) only, or preferentially, in acertain part of the intestinal tract, optionally, in a delayed manner.Examples of encapsulating compositions which can be used includepolymeric substances and waxes. Solid compositions of a similar type canbe employed as fillers in soft and hard-filled gelatin capsules usingsuch excipients as lactose or milk sugar as well as high molecularweight polethylene glycols and the like.

The active ingredient can be in a micro-encapsulated form with one ormore excipients as noted above. The solid dosage forms of tablets,dragees, capsules, pills, and granules can be prepared with coatings andshells such as enteric coatings, release controlling coatings, and othercoatings well known in the formulation art. In such solid dosage formsthe active ingredient can be admixed with at least one inert diluentsuch as sucrose, lactose, or starch. Such dosage forms may comprise, asis normal practice, additional substances other than inert diluents,e.g., tableting lubricants and other tableting aids such a magnesiumstearate and microcrystalline cellulose. In the case of capsules,tablets and pills, the dosage forms may comprise buffering agents. Theymay optionally comprise opacifying agents and can be of a compositionthat they release the active ingredient(s) only, or preferentially, in acertain part of the intestinal tract, optionally, in a delayed manner.Examples of encapsulating agents which can be used include polymericsubstances and waxes.

Dosage forms for topical and/or transdermal administration of acomposition of this disclosure may include ointments, pastes, creams,lotions, gels, powders, solutions, sprays, inhalants, and/or patches.Generally, the active ingredient is admixed under sterile conditionswith a carrier or excipient and/or any needed preservatives and/orbuffers as can be required. Additionally, the present disclosurecontemplates the use of transdermal patches, which often have the addedadvantage of providing controlled delivery of an active ingredient tothe body. Such dosage forms can be prepared, for example, by dissolvingand/or dispensing the active ingredient in the proper medium.Alternatively or additionally, the rate can be controlled by eitherproviding a rate controlling membrane and/or by dispersing the activeingredient in a polymer matrix and/or gel.

Suitable devices for use in delivering intradermal compositionsdescribed herein include short needle devices. Intradermal compositionscan be administered by devices which limit the effective penetrationlength of a needle into the skin. Alternatively or additionally,conventional syringes can be used in the classical mantoux method ofintradermal administration. Jet injection devices which deliver liquidvaccines to the dermis via a liquid jet injector and/or via a needlewhich pierces the stratum corneum and produces a jet which reaches thedermis are suitable. Ballistic powder/particle delivery devices whichuse compressed gas to accelerate the agent in powder form through theouter layers of the skin to the dermis are suitable.

Formulations suitable for topical administration include, but are notlimited to, liquid and/or semi-liquid preparations such as liniments,lotions, oil-in-water and/or water-in-oil emulsions such as creams,ointments, and/or pastes, and/or solutions and/or suspensions. Topicallyadministrable formulations may, for example, comprise from about 1% toabout 10% (w/w) active ingredient, although the concentration of theactive ingredient can be as high as the solubility limit of the activeingredient in the solvent. Formulations for topical administration mayfurther comprise one or more of the additional ingredients describedherein.

A composition described herein can be prepared, packaged, and/or sold ina formulation suitable for pulmonary administration via the buccalcavity. Such a formulation may comprise dry particles which comprise theactive ingredient. Dry powder compositions may include a solid finepowder diluent such as sugar and are conveniently provided in a unitdose form.

Low boiling propellants generally include liquid propellants having aboiling point of below 65° F. at atmospheric pressure. Generally thepropellant may constitute 50 to 99.9% (w/w) of the composition, and theactive ingredient may constitute 0.1 to 20% (w/w) of the composition.The propellant may further comprise additional ingredients such as aliquid non-ionic and/or solid anionic surfactant and/or a solid diluent(which may have a particle size of the same order as particlescomprising the active ingredient).

Compositions described herein formulated for pulmonary delivery mayprovide the active ingredient in the form of droplets of a solutionand/or suspension. Such formulations can be prepared, packaged, and/orsold as aqueous and/or dilute alcoholic solutions and/or suspensions,optionally sterile, comprising the active ingredient, and mayconveniently be administered using any nebulization and/or atomizationdevice. Such formulations may further comprise one or more additionalingredients including, but not limited to, a flavoring agent such assaccharin sodium, a volatile oil, a buffering agent, a surface activeagent, and/or a preservative such as methylhydroxybenzoate. The dropletsprovided by this route of administration may have an average diameter inthe range from about 0.1 to about 200 nanometers.

Formulations described herein as being useful for pulmonary delivery areuseful for intranasal delivery of a composition described herein.Another formulation suitable for intranasal administration is a coarsepowder comprising the active ingredient and having an average particlefrom about 0.2 to 500 micrometers. Such a formulation is administered byrapid inhalation through the nasal passage from a container of thepowder held close to the nares.

Formulations for nasal administration may, for example, comprise fromabout as little as 0.1% (w/w) to as much as 100% (w/w) of the activeingredient, and may comprise one or more of the additional ingredientsdescribed herein. A composition described herein can be prepared,packaged, and/or sold in a formulation for buccal administration. Suchformulations may, for example, be in the form of tablets and/or lozengesmade using conventional methods, and may contain, for example, 0.1 to20% (w/w) active ingredient, the balance comprising an orallydissolvable and/or degradable composition and, optionally, one or moreof the additional ingredients described herein. Alternately,formulations for buccal administration may comprise a powder and/or anaerosolized and/or atomized solution and/or suspension comprising theactive ingredient. Such powdered, aerosolized, and/or aerosolizedformulations, when dispersed, may have an average particle and/ordroplet size in the range from about 0.1 to about 200 nanometers, andmay further comprise one or more of the additional ingredients describedherein.

A composition described herein can be prepared, packaged, and/or sold ina formulation for ophthalmic administration. Such formulations may, forexample, be in the form of eye drops including, for example, a 0.1/1.0%(w/w) solution and/or suspension of the active ingredient in an aqueousor oily liquid carrier or excipient. Such drops may further comprisebuffering agents, salts, and/or one or more other of the additionalingredients described herein. Other opthalmically-administrableformulations which are useful include those which comprise the activeingredient in microcrystalline form and/or in a liposomal preparation.Ear drops and/or eye drops are also contemplated as being within thescope of this disclosure.

Although the descriptions of compositions provided herein areprincipally directed to compositions which are suitable foradministration to humans, it will be understood by the skilled artisanthat such compositions are generally suitable for administration toanimals of all sorts. Modification of compositions suitable foradministration to humans in order to render the compositions suitablefor administration to various animals is well understood, and theordinarily skilled veterinary pharmacologist can design and/or performsuch modification with ordinary experimentation.

Nanostructures and supramolecular complexes described herein aretypically formulated in dosage unit form for ease of administration anduniformity of dosage. It will be understood, however, that the totaldaily usage of the compositions of the present disclosure will bedecided by the attending physician within the scope of sound medicaljudgment. The specific therapeutically effective dose level for anyparticular subject or organism will depend upon a variety of factorsincluding the disease being treated and the severity of the disorder,the activity of the specific active ingredient employed, the specificcomposition employed, the age, body weight, general health, sex, anddiet of the subject, the time of administration, route ofadministration, and rate of excretion of the specific active ingredientemployed, the duration of the treatment, drugs used in combination orcoincidental with the specific active ingredient employed, and likefactors well known in the medical arts.

The compositions described herein can be administered by any suitableroute, including enteral (e.g., oral), parenteral, intravenous,intramuscular, intra-arterial, intramedullary, intrathecal,subcutaneous, intraventricular, transdermal, interdermal, rectal,intravaginal, intraperitoneal, topical (as by powders, ointments,creams, and/or drops), mucosal, nasal, bucal, sublingual; byintratracheal instillation, bronchial instillation, and/or inhalation;and/or as an oral spray, nasal spray, and/or aerosol. In certainembodiments, the compositions are administered by oral administration,intravenous administration (e.g., systemic intravenous injection),regional administration via blood and/or lymph supply, and/or directadministration to an affected site. In general, the most appropriateroute of administration will depend upon a variety of factors includingthe nature of the agent (e.g., its stability in the environment of thegastrointestinal tract), and/or the condition of the subject (e.g.,whether the subject is able to tolerate oral administration).

The exact amount of an agent required to achieve an effective amountwill vary from subject to subject, depending, for example, on species,age, and general condition of a subject, severity of the side effects ordisorder, identity of the particular agent, mode of administration, andthe like. The desired dosage can be delivered three times a day, twotimes a day, once a day, every other day, every third day, every week,every two weeks, every three weeks, or every four weeks. In certainembodiments, the desired dosage can be delivered using multipleadministrations (e.g., two, three, four, five, six, seven, eight, nine,ten, eleven, twelve, thirteen, fourteen, or more administrations).

In certain embodiments, an effective amount of an agent foradministration one or more times a day to a 70 kg adult human maycomprise about 0.0001 mg to about 3000 mg, about 0.0001 mg to about 2000mg, about 0.0001 mg to about 1000 mg, about 0.001 mg to about 1000 mg,about 0.01 mg to about 1000 mg, about 0.1 mg to about 1000 mg, about 1mg to about 1000 mg, about 1 mg to about 100 mg, about 10 mg to about1000 mg, or about 100 mg to about 1000 mg, of an agent per unit dosageform.

In certain embodiments, the agents described herein may be at dosagelevels sufficient to deliver from about 0.001 mg/kg to about 100 mg/kg,from about 0.01 mg/kg to about 50 mg/kg, preferably from about 0.1 mg/kgto about 40 mg/kg, preferably from about 0.5 mg/kg to about 30 mg/kg,from about 0.01 mg/kg to about 10 mg/kg, from about 0.1 mg/kg to about10 mg/kg, and more preferably from about 1 mg/kg to about 25 mg/kg, ofsubject body weight per day, one or more times a day, to obtain thedesired therapeutic and/or prophylactic effect.

It will be appreciated that dose ranges as described herein provideguidance for the administration of provided compositions to an adult.The amount to be administered to, for example, a child or an adolescentcan be determined by a medical practitioner or person skilled in the artand can be lower or the same as that administered to an adult.

Compositions described herein may further include a hydrophilic polymer(e.g., polyethylene glycol (PEG)). The compositions described herein mayfurther include a lipid (e.g., a steroid, a substituted or unsubstitutedcholesterol, or a polyethylene glycol (PEG)-containing material). Incertain embodiments, the lipid included in the compositions is atriglyceride, a driglyceride, a PEGylated lipid, dimyristoyl-PEG2000(DMG-PEG2000), a phospholipid (e.g.,1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)),dioleoylphosphatidylethanolamine (DOPE), a substituted or unsubstitutedcholesterol, a steroid an apolipoprotein, or a combination thereof. Incertain embodiments, the compositions include two components selectedfrom the group consisting of the following components: a hydrophilicpolymer, a triglyceride, a driglyceride, a PEGylated lipid, aphospholipid, a steroid, a substituted or unsubstituted cholesterol, andan apolipoprotein. In certain embodiments, the compositions includethree components selected from the group consisting of the followingcomponents: a hydrophilic polymer, a triglyceride, a driglyceride, aPEGylated lipid, a phospholipid, a steroid, a substituted orunsubstituted cholesterol, and an apolipoprotein. In certainembodiments, the compositions include at least four components selectedfrom the group consisting of the following components: a hydrophilicpolymer, a triglyceride, a driglyceride, a PEGylated lipid, aphospholipid, a steroid, a substituted or unsubstituted cholesterol, andan apolipoprotein. In certain embodiments, the compositions include ahydrophilic polymer, a phospholipid, a steroid, and a substituted orunsubstituted cholesterol. In certain embodiments, the compositionsinclude PEG, DSPC, and substituted or unsubstituted cholesterol. Incertain embodiments, the additional materials are approved by aregulatory agency, such as the U.S. FDA, for human and/or veterinaryuse.

Compositions described herein may be useful in other applications, e.g.,non-medical applications. Nutraceutical compositions described hereinmay be useful in the delivery of an effective amount of a nutraceutical,e.g., a dietary supplement, to a subject in need thereof. Cosmeticcompositions described herein may be formulated as a cream, ointment,balm, paste, film, or liquid, etc., and may be useful in the applicationof make-up, hair products, and materials useful for personal hygiene,etc. Compositions described herein may be useful for other non-medicalapplications, e.g., such as an emulsion, emulsifier, or coating, useful,for example, as a food component, for extinguishing fires, fordisinfecting surfaces, for oil cleanup, and/or as a bulk material.

Agents to be Delivered

Agents that are delivered by the systems (e.g., pharmaceuticalcompositions) described herein may be pharmaceutical (e.g., therapeuticor prophylactic), diagnostic, cosmetic, or nutraceutical agents. Anychemical compound to be administered to a subject or to be contactedwith a tissue or cell may be delivered using the nanostructures,supramolecular complexes, and/or compositions described herein. Theagent may be a small molecule (e.g., a small organic molecule or smallinorganic molecule), protein, peptide, polynucleotide, targeting agent,isotopically labeled chemical compound, vaccine, or immunological agent.The agent may be an agent useful in bioprocessing (e.g., intracellularmanufacturing of proteins, such as a cell's bioprocessing of acommercially useful chemical or fuel). For example, intracellulardelivery of an agent may be useful in bioprocessing by maintaining thecell's health and/or growth, e.g., in the manufacturing of proteins. Anychemical compound to be administered to a subject or contacted with atissue or cell may be delivered to the subject, tissue, or cell usingthe compositions described herein.

Exemplary agents that may be included in a composition described hereininclude, but are not limited to, small molecules, organometalliccompounds, polynucleotides, proteins, peptides, carbohydrates,monosaccharides, oligosaccharides, polysaccharides, nucleoproteins,mucoproteins, lipoproteins, small molecules linked to proteins,glycoproteins, steroids, nucleotides, oligonucleotides, polynucleotides,nucleosides, antisense oligonucleotides, lipids, hormones, vitamins,cells, metals, targeting agents, isotopically labeled chemicalcompounds, drugs (e.g., compounds approved for human or veterinary useby the U.S. Food and Drug Administration as provided in the Code ofFederal Regulations), vaccines, immunological agents, agents useful inbioprocessing, and mixtures thereof. The targeting agents are describedin more detail herein. In certain embodiments, the agents arenutraceutical agents. In certain embodiments, the agents arepharmaceutical agents (e.g., a therapeutic or prophylactic agent). Incertain embodiments, the agent is an antibiotic agent (e.g., ananti-bacterial, anti-viral, or anti-fungal agent), anesthetic, steroidalagent, anti-proliferative agent, anti-inflammatory agent,anti-angiogenesis agent, anti-neoplastic agent, anti-cancer agent,anti-diabetic agent, antigen, vaccine, antibody, decongestant,antihypertensive, sedative, birth control agent, progestational agent,anti-cholinergic, analgesic, immunosuppressant, anti-depressant,anti-psychotic, β-adrenergic blocking agent, diuretic, cardiovascularactive agent, vasoactive agent, non-steroidal, nutritional agent,anti-allergic agent, or pain-relieving agent. Vaccines may compriseisolated proteins or peptides, inactivated organisms and viruses, deadorganisms and viruses, genetically altered organisms or viruses, andcell extracts. Therapeutic and prophylactic agents may be combined withinterleukins, interferon, cytokines, and adjuvants such as choleratoxin, alum, and Freund's adjuvant, etc. In certain embodiments, theagent is a small molecule. In certain embodiments, the agent is ananti-cancer agent (e.g., an anti-cancer agent disclosed in U.S. PatentApplication Publication No. US 2003/065023). In certain embodiments, theagent is doxorubicin.

In certain embodiments, an agent described herein is a polynucleotide.In certain embodiments, the agent is plasmid DNA (pDNA). In certainembodiments, the agent is single-stranded DNA (ssDNA), double-strandedDNA (dsDNA), genomic DNA (gDNA), complementary DNA (cDNA), antisenseDNA, chloroplast DNA (ctDNA or cpDNA), microsatellite DNA, mitochondrialDNA (mtDNA or mDNA), kinetoplast DNA (kDNA), provirus, lysogen,repetitive DNA, satellite DNA, or viral DNA. In certain embodiments, theagent is RNA. In certain embodiments, the agent is small interfering RNA(siRNA). In certain embodiments, the agent is messenger RNA (mRNA). Incertain embodiments, the agent is single-stranded RNA (ssRNA),double-stranded RNA (dsRNA), small interfering RNA (siRNA), precursormessenger RNA (pre-mRNA), small hairpin RNA or short hairpin RNA(shRNA), microRNA (miRNA), guide RNA (gRNA), transfer RNA (tRNA),antisense RNA (asRNA), heterogeneous nuclear RNA (hnRNA), coding RNA,non-coding RNA (ncRNA), long non-coding RNA (long ncRNA or IncRNA),satellite RNA, viral satellite RNA, signal recognition particle RNA,small cytoplasmic RNA, small nuclear RNA (snRNA), ribosomal RNA (rRNA),Piwi-interacting RNA (piRNA), polyinosinic acid, ribozyme, flexizyme,small nucleolar RNA (snoRNA), spliced leader RNA, viral RNA, or viralsatellite RNA. In certain embodiments, the agent is an RNA that carriesout RNA interference (RNAi). The phenomenon of RNAi is discussed ingreater detail, for example, in the following references: Elbashir etal., 2001, Genes Dev., 15:188; Fire et al., 1998, Nature, 391:806;Tabara et al., 1999, Cell, 99:123; Hammond et al., Nature, 2000,404:293; Zamore et al., 2000, Cell, 101:25; Chakraborty, 2007, Curr.Drug Targets, 8:469; and Morris and Rossi, 2006, Gene Ther., 13:553. Incertain embodiments, upon delivery of an RNA into a subject, tissue, orcell, the RNA is able to interfere with the expression of a specificgene in the subject, tissue, or cell. In certain embodiments, the agentis a pDNA, siRNA, mRNA, or a combination thereof.

In certain embodiments, the polynucleotide may be provided as anantisense agent or RNAi. See, e.g., Fire et al., Nature 391:806-811,1998. Antisense therapy is meant to include, e.g., administration or insitu provision of single- or double-stranded polynucleotides, orderivatives thereof, which specifically hybridize, e.g., bind, undercellular conditions, with cellular mRNA and/or genomic DNA, or mutantsthereof, so as to inhibit the expression of the encoded protein, e.g.,by inhibiting transcription and/or translation. See, e.g., Crooke,“Molecular mechanisms of action of antisense drugs,” Biochim. Biophys.Acta 1489(1):31-44, 1999; Crooke, “Evaluating the mechanism of action ofanti-proliferative antisense drugs,” Antisense Nucleic Acid Drug Dev.10(2):123-126, discussion 127, 2000; Methods in Enzymology volumes313-314, 1999. The binding may be by conventional base paircomplementarity, or, for example, in the case of binding to DNAduplexes, through specific interactions in the major groove of thedouble helix (i.e., triple helix formation). See, e.g., Chan et al., J.Mol. Med. 75(4):267-282, 1997.

The RNA and/or RNAi described herein can be designed and/or predictedusing one or more of a large number of available algorithms. To give buta few examples, the following resources can be utilized to design and/orpredict polynucleotides: algorithms found at Alnylum Online; DharmaconOnline; OligoEngine Online; Molecula Online; Ambion Online; BioPredsiOnline; RNAi Web Online; Chang Bioscience Online; Invitrogen Online;LentiWeb Online GenScript Online; Protocol Online; Reynolds et al.,2004, Nat. Biotechnol., 22:326; Naito et al., 2006, Nucleic Acids Res.,34:W448; Li et al., 2007, RNA, 13:1765; Yiu et al., 2005,Bioinformatics, 21:144; and Jia et al., 2006, BMC Bioinformatics, 7:271.

The polynucleotide included in a composition described herein may be ofany size or sequence, and they may be single- or double-stranded. Incertain embodiments, the polynucleotide includes at least about 30, atleast about 100, at least about 300, at least about 1,000, at leastabout 3,000, or at least about 10,000 base pairs. In certainembodiments, the polynucleotide includes not more than about 10,000, notmore than about 3,000, not more than about 1,000, not more than about300, not more than about 100, or not more than about 30 base pairs.Combinations of the above ranges (e.g., at least about 100 and not morethan about 1,000) are also within the scope of the disclosure. Thepolynucleotide may be provided by any suitable means known in the art.In certain embodiments, the polynucleotide is engineered usingrecombinant techniques. See, e.g., Ausubel et al., Current Protocols inMolecular Biology (John Wiley & Sons, Inc., New York, 1999); MolecularCloning: A Laboratory Manual, 2nd Ed., ed. by Sambrook, Fritsch, andManiatis (Cold Spring Harbor Laboratory Press: 1989). The polynucleotidemay also be obtained from natural sources and purified fromcontaminating components found normally in nature. The polynucleotidemay also be chemically synthesized in a laboratory. In certainembodiments, the polynucleotide is synthesized using standard solidphase chemistry. The polynucleotide may be isolated and/or purified. Incertain embodiments, the polynucleotide is substantially free ofimpurities. In certain embodiments, the polynucleotide is at least about50%, at least about 60%, at least about 70%, at least about 80%, atleast about 90%, at least about 95%, or at least about 99% free ofimpurities.

The polynucleotide may be modified by physical, chemical, and/orbiological means. The modifications include methylation,phosphorylation, and/or end-capping, etc. In certain embodiments, themodifications lead to increased stability of the polynucleotide.

Wherever a polynucleotide is employed in the present disclosure, aderivative of the polynucleotide may also be used. These derivativesinclude products resulted from modifications of the polynucleotide inthe base moieties, sugar moieties, and/or phosphate moieties of thepolynucleotide. Modified base moieties include, but are not limited to,2-aminoadenosine, 2-thiothymidine, inosine, pyrrolo-pyrimidine, 3-methyladenosine, 5-methylcytidine, C5-bromouridine, C5-fluorouridine,C5-iodouridine, C5-propynyl-uridine, C5-propynyl-cytidine,C5-methylcytidine, 7-deazaadenosine, 7-deazaguanosine, 8-oxoadenosine,8-oxoguanosine, O(6)-methylguanine, and 2-thiocytidine. Modified sugarmoieties include, but are not limited to, 2′-fluororibose, ribose,2′-deoxyribose, 3′-azido-2′,3′-dideoxyribose, 2′,3′-dideoxyribose,arabinose (the 2′-epimer of ribose), acyclic sugars, and hexoses. Thenucleosides may be strung together by linkages other than thephosphodiester linkage found in naturally occurring DNA and RNA.Modified linkages include, but are not limited to, phosphorothioate and5′-N-phosphoramidite linkages. Combinations of the various modificationsmay be used in a single polynucleotide. These modified polynucleotidesmay be provided by any suitable means known in the art; however, as willbe appreciated by those of skill in the art, the modifiedpolynucleotides may be prepared using synthetic chemistry in vitro.

The polynucleotide described herein may be in any form, such as acircular plasmid, a linearized plasmid, a cosmid, a viral genome, amodified viral genome, or an artificial chromosome.

The polynucleotide described herein may be of any sequence. In certainembodiments, the polynucleotide encodes a protein or peptide. Theencoded protein may be an enzyme, structural protein, receptor, solublereceptor, ion channel, active (e.g., pharmaceutically active) protein,cytokine, interleukin, antibody, antibody fragment, antigen, coagulationfactor, albumin, growth factor, hormone, or insulin, etc. Thepolynucleotide may also comprise regulatory regions to control theexpression of a gene. These regulatory regions may include, but are notlimited to, promoters, enhancer elements, repressor elements, TATAboxes, ribosomal binding sites, and stop sites for transcription. Incertain embodiments, the polynucleotide is not intended to encode aprotein. For example, the polynucleotide may be used to fix an error inthe genome of the cell being transfected.

In certain embodiments, the polynucleotide described herein comprises asequence encoding an antigenic peptide or protein. A compositioncontaining the polynucleotide can be delivered to a subject to induce animmunologic response sufficient to decrease the chance of a subsequentinfection and/or lessen the symptoms associated with such an infection.The polynucleotide of these vaccines may be combined with interleukins,interferon, cytokines, and/or adjuvants described herein.

The antigenic protein or peptides encoded by the polynucleotide may bederived from bacterial organisms, such as Streptococccus pneumoniae,Haemophilus influenzae, Staphylococcus aureus, Streptococcus pyrogenes,Corynebacterium diphtheriae, Listeria monocytogenes, Bacillus anthracis,Clostridium tetani, Clostridium botulinum, Clostridium perfringens,Neisseria meningitidis, Neisseria gonorrhoeae, Streptococcus mutans,Pseudomonas aeruginosa, Salmonella typhi, Haemophilus parainfluenzae,Bordetella pertussis, Francisella tularensis, Yersinia pestis, Vibriocholerae, Legionella pneumophila, Mycobacterium tuberculosis,Mycobacterium leprae, Treponema pallidum, Leptospirosis interrogans,Borrelia burgdorferi, and Camphylobacter jejuni; from viruses, such assmallpox virus, influenza A virus, influenza B virus, respiratorysyncytial virus, parainfluenza virus, measles virus, HIV virus,varicella-zoster virus, herpes simplex 1 virus, herpes simplex 2 virus,cytomegalovirus, Epstein-Barr virus, rotavirus, rhinovirus, adenovirus,papillomavirus, poliovirus, mumps virus, rabies virus, rubella virus,coxsackieviruses, equine encephalitis virus, Japanese encephalitisvirus, yellow fever virus, Rift Valley fever virus, hepatitis A virus,hepatitis B virus, hepatitis C virus, hepatitis D virus, and hepatitis Evirus; and from fungal, protozoan, or parasitic organisms, such asCryptococcus neoformans, Histoplasma capsulatum, Candida albicans,Candida tropicalis, Nocardia asteroides, Rickettsia ricketsii,Rickettsia typhi, Mycoplasma pneumoniae, Chlamydial psittaci, Chlamydialtrachomatis, Plasmodium falciparum, Trypanosoma brucei, Entamoebahistolytica, Toxoplasma gondii, Trichomonas vaginalis, and Schistosomamansoni.

An agent described herein may be covalently or non-covalently attachedto (e.g., complexed to and/or encapsulated in) a nanostructure orsupramolecular complex (e.g., attached to a nanostructure of thesupramolecular complex) described herein, or included in a compositiondescribed herein. In certain embodiments, at least one instance of thenanostructure encapsulates the agent. In certain embodiments, at leastone molecule of the agent is not encapsulated in any instance of thenanostructure. In certain embodiments, upon delivery of the agent into acell, the agent is able to interfere with the expression of a specificgene in the cell.

In certain embodiments, an agent described herein may be a mixture oftwo or more agents that may be useful as, e.g., combination therapies. Acomposition including the mixture can be used to achieve a synergisticeffect. In certain embodiments, the composition including the mixturecan be used to improve the activity and/or bioavailability, reduceand/or modify the metabolism, inhibit the excretion, and/or modify thedistribution of at least one of the two or more agents in a subject,tissue, or cell to which the mixture is administered or dosed. It willalso be appreciated that the composition including the mixture mayachieve a desired effect for the same disorder, and/or it may achievedifferent effects. The two or more agents in the mixture may be usefulfor treating and/or preventing a same disease or different diseasesdescribed herein.

The compositions (e.g., pharmaceutical compositions) described hereincan be administered concurrently with, prior to, or subsequent to theone or more agents (e.g., pharmaceutical agents). Each one of the agentsmay be administered at a dose and/or on a time schedule determined forthat agent. The agents may also be administered together with each otherand/or with the composition described herein in a single dose oradministered separately in different doses. The particular combinationto employ in a regimen will take into account compatibility of theagents and/or the desired therapeutic and/or prophylactic effect to beachieved. In general, it is expected that the agents utilized incombination be utilized at levels that do not exceed the levels at whichthey are utilized individually. In some embodiments, the levels utilizedin combination will be lower than those utilized individually.

Targeting Agents

Since it is often desirable to target a particular cell, collection ofcells, or tissue, a composition described herein may further includetargeting moieties or targeting agents. In certain embodiments, ananostructure described herein (including a nanostructure moiety of asupramolecular complex described herein) is modified to includetargeting moieties or targeting agents. For example, a targeting moietyor targeting agent may be included throughout a nanostructure orsupramolecular complex (e.g., throughout a nanostructure of thesupramolecular complex) described herein or may be only at the surface(e.g., outer or inner surface) of the nanostructure or supramolecularcomplex (e.g., at the surface of a nanostructure of the supramolecularcomplex). A targeting agent may be a protein, peptide, carbohydrate,glycoprotein, lipid, small molecule, or polynucleotide, and a targetingmoiety may be a fragment of the targeting agent. The targeting moiety ortargeting agent may be used to target specific cells or tissues or maybe used to promote endocytosis or phagocytosis of the nanostructureand/or supramolecular complex. The targeting moieties or targetingagents include the ones known in the art. See, e.g., Cotten et al.,Methods Enzym. 217:618, 1993. Examples of the targeting moieties andtargeting agents include, but are not limited to, antibodies, proteins,peptides, carbohydrates, small molecules, metals, receptor ligands,sialic acid, aptamers, and fragments thereof. If a targeting moiety ortargeting agent is included throughout a nanostructure or supramolecularcomplex, the targeting agent may be included in the mixture that is usedto form the nanostructure or supramolecular complex. If the targetingagent is only on the surface of a nanostructure or supramolecularcomplex, the targeting agent may be associated with (e.g., by covalentor non-covalent (e.g., electrostatic, hydrophobic, hydrogen bonding, vander Waals, π-π stacking) interactions) the nanostructure orsupramolecular complex using standard chemical techniques.

Adducts of a Nanostructure and an Agent

The present disclosure contemplates that the nanostructures describedherein (including the nanostructure moieties of the supramolecularcomplexes described herein) are useful in the delivery of an agentdescribed herein (e.g., a small molecule, peptide, protein, or apolynucleotide) to a subject, tissue, or cell. Without wishing to bebound by any particular theory, the nanostructures have severaldesirable properties that make a composition that includes thenanostructures and an agent suitable for delivering the agent to asubject, tissue, or cell. Encapsulation of an agent within ananostructure described herein may have desirable properties fordelivering an agent to a subject, tissue, or cell, including protectionfrom degradation of the agent by ubiquitous nucleases, passive andactive targeting, and/or evasion of endosomal Toll-like receptors. Otherdesirable properties include: 1) the ability of the nanostructures toform an adduct with and “protect” the agent that may otherwise be labile(e.g., labile at least due to chemical and/or enzymatical (e.g., bynucleases) degradation); 2) the ability of the nanostructures to bufferthe pH in an endosome of the cell; 3) the ability of the nanostructuresto act as a “proton sponge” and cause endosomolysis; and 4) the abilityof the nanostructures to substantially neutralize the negative orpositive charges of the agent. Challenges to the efficient delivery ofan agent exist, including particle dissociation via serum proteins,cellular uptake, endosomal escape, and appropriate intracellulardisassembly. To address some of these challenges, single parameterstudies that evaluate the effect of chemical structure on a singlebiological property or on delivery performance have been reported.Furthermore, high-throughput synthetic methods have been exploited forthe accelerated discovery of potent lipid nanoparticles (LNPs) andevaluation of structure activity relationships (SARs). In spite of theseefforts, the relationships between physicochemical properties ofnanoparticles and biological barriers, and that between biologicalbarriers and gene silencing activity remain unclear. This lack ofclarity has also resulted in poor in vitro-in vivo translation.

In certain embodiments, a nanostructure described herein encapsulates anagent described herein. In certain embodiments, the ratio of the amountof a nanostructure described herein to the amount of an agentencapsulated in the nanostructure is at least about 1:1, at least about2:1, at least about 5:1, at least about 10:1, at least about 20:1, atleast about 50:1, at least about 100:1, at least about 200:1, or atleast about 500:1 mol/mol. In certain embodiments, the ratio of thenanostructure or supramolecular complex to the agent is not more thanabout 500:1, not more than about 200:1, not more than about 100:1, notmore than about 50:1, not more than about 20:1, not more than about10:1, not more than about 5:1, not more than about 2:1, or not more thanabout 1:1 mol/mol. Combinations of the above ranges (e.g., at leastabout 1:1 and not more than about 100:1) are also within the scope ofthe disclosure.

A nanostructure and agent described herein may form an adduct. An adductmay be formed by covalently attaching an agent to a nanostructure or bynon-covalent interactions (e.g., electrostatic interactions, hydrophobicinteractions, hydrogen bonding, van der Waals interactions, and/or π-πstacking) between an agent and a nanostructure. An agent may becontacted with a nanostructure, or the components thereof (e.g., ligandsof Formula (A) and transition metal ions, and optionally anioniccounterions), under conditions suitable to form an adduct.

Micelles, Liposomes, and Lipoplexes

A composition including a nanostructure and agent described herein maybe in the form of a micelle or liposome. In certain embodiments, thenanostructures are in the form of a micelle or liposome. An agentdescribed herein may be inside a micelle or liposome, and ananostructure described herein may be inside the micelle or liposome. Incertain embodiments, in a micelle or liposome, an agent is encapsulatedin a nanostructure. Micelles and liposomes are typically useful indelivering an agent, such as a hydrophobic agent, to a subject, tissue,or cell. When the micelle or liposome is complexed with (e.g.,encapsulates or covers) a polynucleotide, the resulting complex may bereferred to as a “lipoplex.” Many techniques for preparing micelles andliposomes are known in the art, and any such method may be used to makemicelles and liposomes.

In certain embodiments, liposomes are formed through spontaneousassembly. In some embodiments, liposomes are formed when thin lipidfilms or lipid cakes are hydrated and stacks of lipid crystallinebilayers become fluid and swell. The hydrated lipid sheets detach duringagitation and self-close to form large, multilamellar vesicles (LMV).This may prevent interaction of water with the hydrocarbon core of thebilayers at the edges. Once these liposomes have formed, reducing thesize of the liposomes can be modified through input of sonic energy(sonication) or mechanical energy (extrusion). See, e.g., Walde, P.“Preparation of Vesicles (Liposomes)” In Encylopedia of Nanoscience andNanotechnology; Nalwa, H. S. Ed. American Scientific Publishers: LosAngeles, 2004; Vol. 9, pp. 43-79; Szoka et al., “Comparative Propertiesand Methods of Preparation of Lipid Vesicles (Liposomes)” Ann. Rev.Biophys. Bioeng. 9:467-508, 1980; each of which is incorporated hereinby reference. The preparation of lipsomes may involve preparing ananostructure described herein for hydration, hydrating thenanostructures with agitation, and sizing the vesicles to achieve ahomogenous distribution of liposomes. A nanostructure described hereinmay be first dissolved in a solvent in a container to result in ahomogeneous mixture. The solvent is then removed to form a film. Thisfilm is thoroughly dried to remove residual amount of the solvent, e.g.,by placing the container in vacuo for a period of time. Hydration of thefilm may be accomplished by adding an aqueous medium and agitating theresulting mixture. Disruption of LMV suspensions using sonic energytypically produces small unilamellar vesicles (SUV) with diameters inthe range of 15-50 nm. Lipid extrusion is a technique in which a lipidsuspension is forced through a polycarbonate filter with a defined poresize to yield particles having a diameter near the pore size of thefilter used. Extrusion through filters with 100 nm pores typicallyyields large, unilamellar vesicles (LUV) with a mean diameter of 120-140nm. In certain embodiments, the amount ofa nanostructure describedherein in the liposome is between about 30 mol % and about 80 mol %,between about 40 mol % and about 70 mol %, or between about 60 mol % andabout 70 mol %, inclusive. In certain embodiments, the nanostructuresfurther complexes an agent, such as a small molecule.

Liposomes and micelles may also be prepared according to methods in thefollowing scientific papers: Narang et al., “Cationic Lipids withIncreased DNA Binding Affinity for Nonviral Gene Transfer in Dividingand Nondividing Cells,” Bioconjugate Chem. 16:156-68, 2005; Hofland etal., “Formation of stable cationic lipid/DNA complexes for genetransfer,” Proc. Natl. Acad. Sci. USA 93:7305-7309, July 1996; Byk etal., “Synthesis, Activity, and Structure—Activity Relationship Studiesof Novel Cationic Lipids for DNA Transfer,” J. Med. Chem. 41(2):224-235,1998; Wu et al., “Cationic Lipid Polymerization as a Novel Approach forConstructing New DNA Delivery Agents,” Bioconjugate Chem. 12:251-57,2001; Lukyanov et al., “Micelles from lipid derivatives of water-solublepolymers as delivery systems for poorly soluble drugs,” Advanced DrugDelivery Reviews 56:1273-1289, 2004; Tranchant et al., “Physicochemicaloptimisation of plasmid delivery by cationic lipids,” J. Gene Med.6:S24-S35, 2004; van Balen et al., “Liposome/Water Lipophilicity:Methods, Information Content, and Pharmaceutical Applications,”Medicinal Research Rev. 24(3):299-324, 2004.

Gels

Gels are much different from classical mechanics of materials, in thatthe timescale associated with the imposed stress or strain can affectthe mechanical response by several orders of magnitude. Theseviscoelastic characteristics of gels are significant to manyapplications, and better understanding of the spatial and temporalmechanisms which effect desirable mechanical properties will lead tobetter materials designs. In gels, the timescales over which mechanicalinteractions occur are highly important; materials can have apparentfluid-like properties at long timescales yet apparent solid-likeproperties at short timescales. Typically, gels possess littlelong-range spatial ordering. Instead, the molecules in the gels arrangethemselves in a wide array of spatial conformations. This spatialheterogeneity effects a corresponding temporal heterogeneity: uponapplication of a stress, the material begins to relax by deforming. Eachof the local conformations relax at a distinct timescale. The mechanicalproperties (e.g., viscoelastic properties) of gels are important for thegels to be used in various applications. For example, it has been shownthat substrate elasticity can determine mesenchymal stem celldifferentiation (Engler et al. Cell, 2006, 126, 677-689). There is aneed for gels with “designer viscoelasticity,” the ability to creategels with a specifically engineered viscoelastic spectrum. Conventionalmethods for designing the mechanical properties of gels include changingthe molecular weight or molecular weight distribution of the polymermatrix, increasing the degree of crosslinking between polymer chains,changing the stiffness of the polymer backbone, and changing thebulkiness of the side groups. However, these conventional techniquesalter the properties of the polymer matrix such that they add otherfeatures which may be undesirable.

Coordination chemistry typically features bonds between metals andligands that are intermediate in bond-energy between covalent bonds andnon-covalent interactions (e.g., van der Waals interactions andH-bonding). Such bonds can be reversible or dynamic under appropriateconditions; they have been extensively used for the formation of a classof gel networks—metallogels—that features stimuli-responsiveproperties.¹⁻³² Due to their low branch functionality and dynamic bonds,most metallogels are soft elastic materials (storage moduli of G′≤20 kPaat ˜2-10 wt. % polymer network) that often display viscous flow behaviorat low shear strain frequencies.^(6,7,21,26,29) These weak mechanicalproperties severely limit the possible applications of metallogels; thedesirable dynamic properties inevitably come at the expense ofstructural integrity.

Recently, transition metal-organic ligand complexes have been suggestedto reinforce the mechanical properties and self-healing nature of marinemussel adhesion fibers (“byssi”) (Harrington et al. Science, 2010, 328,216-220; Harrington et al. The Journal of Experimental Biology, 2007,210, 4307-4318; Holten-Andersen et al. Nature Materials, 2007, 6,669-672; Lee et al. Proceedings of the National Academy of Sciences ofthe United States of America, 2006, 103, 12999-13003). Efforts have beenmade to mimic the extraordinary mechanical properties of the byssi usingsimplified synthetic analogs (Holten-Andersen et al. Proceedings of theNational Academy of Sciences of the United States of America, 2011, 108,2651-2655; Holten-Andersen et al., Journal of Materials Chemistry B,2014, 2, 2467-2472; Lee et al. Annual Review of Materials Research,2011, 41, 99-132; Barrett et al. Advanced functional materials, 2013,23, 1111-1119; Fullenkamp et al. Macromolecules, 2013, 46, 1167-1174).Craig et al. has reported the formation and dynamic mechanicalproperties of metallo-supramolecular networks formed by mixtures ofbis-Pd(II) and Pt(II) cross-linkers with poly(4-vinylpyridine) in DMSO.These networks have relaxation timescales that vary across severalorders of magnitude. Also reported are that the kinetics of metal-liganddissociation could be used to tune the apparent mechanical properties ofa metallogel within a relevant timescale.²⁴⁻²⁶ Furthermore, it has beenshown that the thermodynamics of coordination can serve as a partiallycomplementary parameter to tune the mechanical properties of gels.²⁶Though manipulation of the kinetic and thermodynamic properties ofindividual metal-ligand bonds offers one way to modulate bulkproperties, this strategy is ultimately limited in terms of themagnitude of changes that can be induced. Furthermore, it requires thedesign and synthesis of an assortment of ligand architectures and/or theuse of different metals to induce changes in network behavior, which maynot be compatible with a given application.

Tetrazine derivatives are another ligand that is useful in transitionmetal-ligand complexes. Interest in tetrazine reactivity has recentlyresurged largely due to its use in bioconjugate and polymer chemistry(Wollack, J. W.; Monson, B. J.; Dozier, J. K.; Dalluge, J. J.; Poss, K.;Hilderbrand, S. A.; Distefano, M. D. Chemical Biology & Drug Design2014, 84, 140; Darko, A.; Wallace, S.; Dmitrenko, O.; Machovina, M. M.;Mehl, R. A.; Chin, J. W.; Fox, J. M. Chemical Science 2014, 5, 3770; Wu,H.; Cisneros, B. T.; Cole, C. M.; Devaraj, N. K. Journal of the AmericanChemical Society 2014, 136, 17942; Hansell, C. F.; Espeel, P.;Stamenović, M. M.; Barker, I. A.; Dove, A. P.; Du Prez, F. E.; O'Reilly,R. K. Journal of the American Chemical Society 2011, 133, 13828;Blackman, M. L.; Royzen, M.; Fox, J. M. Journal of the American ChemicalSociety 2008, 130, 13518; Cok, A. M.; Zhou, H.; Johnson, J. A.Macromolecular Symposia 2013, 329, 108; Zhou, H.; Woo, J.; Cok, A. M.;Wang, M.; Olsen, B. D.; Johnson, J. A. Proceedings of the NationalAcademy of Sciences 2012). Certain tetrazine species are known for theirbinding to various metal ions; specifically,3,6-bis(2-pyridyl)-1,2,4,5-tetrazines (bptz), has been studied foradditional purposes by several groups as ligands in self-assembledstructures. The Dunbar group reported the synthesis of moleculartriangles, squares, and pentagons using bptz and various metal ionsincluding Fe²⁺, Ni²⁺, and Ag⁺, respectively. Additional accounts ofusing bptz include gold surface modification and its use as a ligand forrhenium to use its MLCT for study in photoinduced charge separation(Skomski, D.; Tempas, C. D.; Smith, K. A.; Tait, S. L. Journal of theAmerican Chemical Society 2014, 136, 9862; Li, G.; Parimal, K.; Vyas,S.; Hadad, C. M.; Flood, A. H.; Glusac, K. D. J. Am. Chem. Soc. 2009,131, 11656).

It has previously reported that covalent A₂+B₃ type end-linked polymernetworks was synthesized using a tris-bptz trifunctional crosslinker andnorbomene-terminated poly(ethylene glycol) (PEG) telechelic polymers(Hansell, C. F.; Espeel, P.; Stamenović, M. M.; Barker, I. A.; Dove, A.P.; Du Prez, F. E.; O'Reilly, R. K. Journal of the American ChemicalSociety 2011, 133, 13828; Cok, A. M.; Zhou, H.; Johnson, J. A.Macromolecular Symposia 2013, 329, 108; Zhou, H.; Woo, J.; Cok, A. M.;Wang, M.; Olsen, B. D.; Johnson, J. A. Proceedings of the NationalAcademy of Sciences 2012; Zhou, H.; Johnson, J. A. Angew. Chem., Int.Ed. 2013, 52, 2235). Strained alkenes and tetrazines undergo facileinverse-electron demand Diels-Alder reactions with the extrusion ofnitrogen, which make them useful for efficiently synthesizingcatalyst-free, two component polymer networks. Subsequent work by Ansethand coworkers used this chemistry to construct cytocompatible gels thatcould be photochemically patterned (Alge, D. L.; Azagarsamy, M. A.;Donohue, D. F.; Anseth, K. S. Biomacromolecules 2013, 14, 949). However,there are no known references of bptz-metal coordination as a mode ofcrosslinking for the formation of end-linked polymer networks and theapplications thereof.

A key component of polymer network structures that cannot be readilyaddressed by traditional metallogels is the network branchfunctionality, f, which is the average number of chains that emanatefrom junctions within a network. According to the phantom network modelof rubber elasticity, the modulus of a gel increases with f.³³ Intraditional metallogels, the junctions are single metal centers (FIG.1A, left); f is dictated by the number of ligands that can bind to thatmetal, which is typically limited to values between two and four. Thus,metallogels are typically very soft materials, and it is very difficultto tune f without complete redesign of the network components.

It was envisioned that dramatic enhancements in f could be realized ifnetwork junctions were created through metal-ligand self-assembly intohigher-order cage-like structures (FIG. 16A, right panel). Such“suprametallogels” would retain the dynamic properties of metallogelswhile potentially featuring broadly tunable branch architectures andenhanced mechanical properties. Indeed, Mother Nature uses hierarchical,multivalent assembly of weakly interacting species to produce biologicalgels with robust mechanical properties and dynamic behavior. Similarconcepts have been adopted to increase the mechanical stability ofsynthetic networks;³⁴ however, to our knowledge, the use of programmedmetallosupramolecular assembly for gelation has not been explored. Asdemonstrated here, such an approach is attractive because it enablestuning of gel properties over a wide range using the same metal andpolymer, and very simple ligand modifications.

Numerous examples of ligand-metal combinations are known to providediscrete self-assembled cage-like structures.³⁵⁻⁴⁸ Reports of Fujita andcoworkers on the formation of M₁₂L₂₄ spherical cages from the assemblyof twenty-four phenyl-3,5-bis-(para-pyridine) ligands (e.g., L-para andL1, FIG. 16B) and 12 Pd²⁺ atoms were inspiring. In several studies,these authors have shown that these assemblies can be synthesized inquantitative yield, that they are robust towards a diverse range ofligand substitutions (R in FIG. 16B),^(49,50) and that they can serve assmall molecule hosts and nano-reactors.³⁶ Thus, incorporation of thesesupramolecular cages as junctions within a polymer network could affordsuprametallogels with additional advantages—aside from mechanicalones—over conventional metallogels such as the ability to encapsulateand release species within the junction cages, or conduct reactions inconfined spaces within the gel.

Two questions were to be answered. First, if bis-pyridyl moietiessimilar to those used by Fujita et al.³⁶ are appended onto the ends oflinear polymer chains (e.g., macromers B-3 and B-4, FIG. 16C), willthose polymer chains form suprametallogels in the presence of Pd²⁺through the self-assembly of the polymer chain ends? This question isnon-trivial, because gelation has the potential to dramatically perturbthe dynamics of cage self-assembly. Second, if an isomeric bis-pyridylligand, one that does not generate spherical cages but an alternativeassembly, can be used to tune the network branch functionality in arational manner? For example, in contrast to the defined 120° bite angleof the para-pyridine isomers, the corresponding meta isomers (L-meta andL2, FIG. 16B) have infinitely many possible bite angles between 0° and240° depending on the relative orientation of the two pyridines. Ditopicligands with similar geometry are known to self-assemble into M₂L₄paddlewheels (FIG. 16B) with several types of metal ions, includingPd²⁺.⁵¹⁻⁶⁵ The 1-hydroxymethyl derivative of L-meta (L2, FIG. 16B) wassynthesized, and it was confirmed that it quantitatively forms M₂L4paddlewheels in the presence of Pd²⁺ ions. Thus, assuming no networkdefects and perfect self-assembly, polymers terminated with ligand L1(macromer B-3, FIG. 16C) may provide suprametallogels with f=24cage-like junctions, while analogous polymers terminated with ligand L2(macromer B-4, FIG. 16C) may provide suprametallogels with f=4paddlewheel junctions. In other words, a small difference in macromerligand structure may provide materials with different bulk properties.Notably, this approach stands in stark contrast to gels that are formedvia pre-assembly of metal-ligand-derived nanostructures that featureorthogonal groups for subsequent crosslinking.⁶⁶⁻⁶⁸ Presented here arethe first examples of gelation induced through metal-ligand bondformation and concomitant metallosupramolecular assembly (e.g., inducedexclusively through metal-ligand bond formation and concomitantmetallosupramolecular assembly).

The present disclosure also provides a new use of bptz as a ligandappended to PEG that binds to metals as a method for gelation. Inaddition, it has been shown that the bptz motif can act as abifunctional moiety: first, as a ligand for coordinating metal ions andsecond, as a reactive site for functionalization.

Therefore, in another aspect, the present disclosure providescompositions that are gels or in the form of a gel (e.g., hydrogel), thecompositions including a supramolecular complex and optionally an agentdescribed herein. The gels described herein are suprametallogels. Asupramolecular complex described herein and/or an adduct of asupramolecular complex and an agent (supramolecule-agent adduct) may beable to form a gel upon contacting a fluid. In certain embodiments, thefluid is a suitable solvent described herein (e.g., water). In certainembodiments, the supramolecular complex and/or supramolecule-agentadduct form a gel at least through the complexation of ligands ofFormula (A) and transition metal ions and optionally also through othernon-covalent interrelations (e.g., electrostatic interactions,hydrophobic interactions, hydrogen bonding, van der Waals interactions,and/or π-π stacking). A supramolecular complex and/orsupramolecule-agent adduct described herein may form a gel uponcontacting a fluid when the concentration of the supramolecular complexand/or supramolecule-agent adduct in the fluid is a suitableconcentration described herein (e.g., between about 10 and about 500millimoles of a reactant or reagent (e.g., a ligand of Formula (A); amacromer of Formula (B) or (C); or a transition metal salt) per liter ofthe fluid, inclusive). The structure of a gel described herein includesthe primary structure (e.g., the structure of the nanostructure moietiesof the gel) and secondary structure (e.g., the way how differentinstances of the nanostructure moieties are connected by divalentlinkers Y and the degree of entanglement of the supramolecular complexesin the gel). In a supramolecular complex, an instance of divalent linkerY may be intrastructural or interstructural. An intrastructural instanceof Y forms a loopy structure, whereas an interstructural instance of Yforms a chain structure. When all instances of divalent linker Yincluded in a gel described herein are intrastructural (e.g., when theconcentration of the nanostructure moieties of a supramolecular complexin the fluid is below a critical concentration (in other words, under anoverly high dilution), a “loopy nanostructure” forms. In certainembodiments, the critical concentration is about 5 mM, about 10 mM,about 15 mM, or about 25 mM. In certain embodiments, a gel describedherein does not include loopy nanostructures. A supramolecular complexmay include more than two instances of the nanostructure moietycovalently connected by more than one interstructural instance of Y. Aninstance of the supramolecular complex may entangle within itself, andtwo or more instances of the supramolecular complex may also entangle.The entangled supramolecular complex(es) form a molecular network thatincludes cavities, which may be filled with a fluid when thesupramolecular complex(es) are contacted with the fluid, and thesupramolecular complex(es) may retain the fluid and be swelled, ratherthan be dissolved, by the fluid to form a gel. A high degree ofentanglement of the supramolecular complexes may be beneficial for theformation of a gel when the supramolecular complexes are contacted witha fluid. A high ratio of the number of interstructural divalent linkersY to the number of intrastructural divalent linkers Y may also bebeneficial for the formation of a gel at least because such a high ratiomay increase the entanglement of the supramolecular complexes in thegel. In certain embodiments, at least about 50%, at least about 60%, atleast about 70%, at least about 80%, or at least about 90% of allinstances of divalent linker Y included in a gel described herein areinterstructural.

Conventional gels (e.g., gels formed by swelling a covalentlycross-linked polymer with a fluid) are typically not able to flow undera suitable stress (a suitable shear stress) and to self-heal whendamaged. The gels described herein are advantageous over theconventional gels at least in that the gels described herein are able toflow under a suitable stress and to self-heal when damaged. While aconventional gel is usually thermally irreversible, the gels describedherein are thermoreversible. A change in physical and/or chemicalconditions (e.g., stress, temperature, and/or concentration) from afirst condition to a second condition may result in a change in thedegree of gelation of a gel described herein from a first degree ofgelation to a second degree of gelation. A change in physical and/orchemical conditions (e.g., stress, temperature, and/or concentration)from the second condition to the first condition may result in a changein the degree of gelation of a gel described herein from the seconddegree of gelation to the first degree of gelation. The molecularnetwork of a gel described herein may reversibly deform at least throughweakening or strengthening, or breaking or reforming, the coordinationbonds between the ligands of Formula (A) and the transition metal ionsby changing physical and/or chemical conditions. In contrast, thecovalent bonds in a conventional gel typically cannot be reversiblyweakened or strengthened, or broken or reformed, by changing physicaland/or chemical conditions. The aggregation of the molecules in a geldescribed herein is more dynamic, compared to the aggregation of themolecules in a conventional gel, and the more dynamic aggregation in agel described herein is at least due to the non-covalent interactionsbetween the molecules therein. Conventional gels typically cannot beeasily characterized using spectroscopic techniques. In contrast, thegels described herein allow facile characterizations using readilyavailable spectroscopic techniques (e.g., UV-vis absorption spectroscopyand Raman spectroscopy) under various conditions. Combination ofchemical spectroscopy with mechanical tests will then beget spatialstructure-temporal structure-mechanical property relationships; thisallows for shape design criteria for engineering the mechanicalproperties of gels (vis-à-vis modulating the modes of the relaxationspectrum).

The gels described herein are also advantageous over conventionalnanostructures (e.g., nanoparticles without divalent linkers that arecovalently attached to different instances of the nanoparticles).Individual instances of a conventional nanostructure are not covalentlylinked to each other, and therefore, the conventional nanostructurestypically lack robustness and storage modulus. Conversely, in a geldescribed herein, at least two instances of the nanostructure arecovalently linked by at least one instance of divalent linker Y. Thecovalent bonding between the individual nanostructures in a geldescribed herein is stronger than the non-covalent interactions, if any,between the individual nanostructures in conventional nanostructures.Therefore, compared to conventional nanostructures, the gels describedherein show higher robustness and/or higher storage modulus.

The supramolecular complexes and compositions (e.g., gels) may also beable to absorb a large amount of a fluid (e.g., absorb at least 100times by weight of the fluid, compared to the weight of thesupramolecular complex or the dry weight of the composition (weight ofthe composition minus the weight of the fluid included in thecomposition) and, therefore, may be useful as super-absorbent materials.

Kits

Also described herein are kits (e.g., packs). The kits provided maycomprise (1) a transition metal salt, ligand of Formula (A); a macromerof Formula (B); a macromer of Formula (C); a nanostructure; asupramolecular complex; and/or a composition (e.g., gel) describedherein; and (2) a container (e.g., a vial, ampule, bottle, syringe,and/or dispenser package, or other suitable container). In someembodiments, a kit described herein further includes a second containercomprising an excipient for dilution or suspension of a nanostructure,supramolecular complex, or composition described herein. In someembodiments, the nanostructure, supramolecular complex, or compositionprovided in the first container and the nanostructure, supramolecularcomplex, or composition provided in the second container are combined toform one unit dosage form.

In certain embodiments, the kits described herein are useful fordelivering an agent to a subject, tissue, or cell. In certainembodiments, the kits are useful for delivering an agent to a targettissue described herein. In certain embodiments, the kits are useful fortreating a disease described herein. In certain embodiments, the kitsare useful for preventing a disease described herein.

In certain embodiments, the described kits further include instructionsfor administering a nanostructure, supramolecular complex, orcomposition described herein. The kits may also include information asrequired by a regulatory agency such as the U.S. Food and DrugAdministration (FDA). In certain embodiments, the information includedin the kits is prescribing information. In certain embodiments, thekits, including the instructions, provide for delivering an agentdescribed herein to a subject, tissue, or cell. In certain embodiments,the kits, including the instructions, provide for treating a diseasedescribed herein. In certain embodiments, the kits, including theinstructions, provide for preventing a disease described herein. The kitdescribed herein may include one or more agents described herein as aseparate composition.

Methods of Preparing the Nanostructures, Supramolecular Complexes, andGels; and the Nanostructures, Supramolecular Complexes, and GelsPrepared by the Methods

The nanostructures, supramolecular complexes, and compositions (e.g.,gels) described herein may be prepared by complexation reactions. Inanother aspect, the present disclosure provides methods of preparing ananostructure (Method A), the methods including reacting a ligand ofFormula (A), or a salt thereof, with a transition metal salt to providethe nanostructure.

In certain embodiments, the transition metal salt is salt of atransition metal ion described herein. In certain embodiments, thetransition metal salt is a solvate (e.g., hydrate). In certainembodiments, the transition metal salt is not a solvate (e.g., isanhydrous). In certain embodiments, the transition metal salt is a Pd(e.g., Pd(II)) salt. In certain embodiments, the transition metal saltis a Ni (e.g., Ni(II)) salt. In certain embodiments, the transitionmetal salt is a Fe (e.g., Fe(II) or Fe(III)) salt. In certainembodiments, the transition metal salt is a Rh (e.g., Rh(l)) salt, Ir(e.g., Ir(I)) salt, Pt (e.g., Pt(II)) salt, or Au (e.g., Au(III)) salt.In certain embodiments, the transition metal salt is a Cd (e.g., Cd(II))salt, Co (e.g., Co(III)) salt, or Cu (e.g., Cu(I) or Cu(II)) salt. Incertain embodiments, the transition metal salt includes an anioniccounterion described herein (e.g., ClO₄ ⁻, NO₃ ⁻, TfO⁻, BF₄ ⁻, PF₄ ⁻,PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻, AcO⁻, F⁻, Cl⁻, Br⁻, or I⁻). In certainembodiments, the transition metal salt is Pd(NO₃)₂, or a solvate orhydrate thereof (e.g., Pd(NO₃)₂.H₂O or Pd(NO₃)₂.2H₂O). In certainembodiments, the transition metal salt is Ni(ClO₄)₂, or a solvate orhydrate thereof. In certain embodiments, the transition metal salt isFe(ClO₄)₂, or a solvate or hydrate thereof.

In another aspect, the present disclosure provides methods of preparinga supramolecular complex (Method B), the methods including complexing amacromer of Formula (B) or (C), or a salt thereof, with a transitionmetal salt to provide the supramolecular complex.

In another aspect, the present disclosure provides methods of preparinga gel (Method C), the methods including complexing a macromer of Formula(B) or (C), or a salt thereof, with a transition metal salt in thepresence of a fluid to provide the gel. In certain embodiments, the stepof complexing of Method C further comprises the presence of an agent(e.g., a small molecule, such as an anticancer agent (e.g.,doxorubicin)). In certain embodiments, the step of complexing of MethodC further comprises crosslinking the macromer, before or after the stepof complexing, in the presence of a crosslinking agent (crosslinker). Incertain embodiments, the crosslinker is a norbornene crosslinker (e.g.,tri-norbornene crosslinker).

The step(s) of the methods of preparing the nanostructures,supramolecular complexes, and/or compositions (e.g., gels) describedherein may be performed under any suitable conditions. A suitablecondition is a combination of physical and chemical parameters underwhich an intended product (e.g., a nanostructure, supramolecularcomplex, or composition (e.g., gel) described herein) or intermediatemay be formed using the methods.

A suitable condition may include the absence of a solvent (i.e., neat).A suitable condition may include a suitable solvent. In certainembodiments, the suitable solvent is an organic solvent. In certainembodiments, the suitable solvent is an inorganic solvent (e.g., water).In certain embodiments, the suitable solvent is an aprotic organicsolvent (e.g., acetonitrile, N,N-dimethylformamide (DMF),N,N-dimethylacetamide (DMA), N-methyl-2-pyrrolidone (NMP), dimethylsulfoxide (DMSO), tetrahydrofuran (THF), 2-methyl-tetrahydrofuran,tetrahydropyran, dioxane, diethyl ether, methyl t-butyl ether (MTBE),dimethoxyethane (DME), diglyme, acetone, butanone, dichloromethane,chloroform, carbon tetrachloride, or 1,2-dichloroethane). In certainembodiments, the suitable solvent is DMSO. In certain embodiments, thesuitable solvent is acetonitrile. In certain embodiments, the suitablesolvent is a protic organic solvent (e.g., an alcohol, such as methanol,ethanol, propanol, or butanol). In certain embodiments, the suitablesolvent is a mixture of two or more solvents (e.g., a mixture of waterand DMSO). In certain embodiments, the suitable solvent is commerciallyavailable.

A suitable condition may also include a suitable concentration of aligand of Formula (A) or macromer of Formula (B) or (C) in a fluid orsuitable solvent. In certain embodiments, the concentration of a ligandof Formula (A) or macromer of Formula (B) or (C), or a salt thereof, ina fluid or suitable solvent is at least about 1, at least about 3, atleast about 10, at least about 15, at least about 25, at least about 50,at least about 100, at least about 250, at least about 500, or at leastabout 1,000 millimoles per liter of the fluid or suitable solvent. Incertain embodiments, the concentration of the a ligand of Formula (A) ormacromer of Formula (B) or (C), or a salt thereof, in a fluid orsuitable solvent is not more than about 1,000, not more than about 500,not more than about 250, not more than about 100, not more than about50, not more than about 25, not more than about 15, not more than about10, not more than about 3, or not more than about 1 millimoles per literof the fluid or suitable solvent. Combination of the above ranges (e.g.,between about 5 and about 500 millimoles per liter of the fluid orsuitable solvent, inclusive) is also within the scope of the presentdisclosure. In certain embodiments, the concentration of a ligand ofFormula (A) or macromer of Formula (B) or (C), or a salt thereof, in afluid or suitable solvent is between 5 and 500, between 5 and 100,between 10 and 500, between 15 and 500, inclusive, or at least about 10or about 15 millimoles per liter of the fluid or suitable solvent,inclusive.

A suitable condition may also include a suitable molar ratio of (1) theligand of Formula (A) or macromer of Formula (B) or (C) to (2) thetransition metal salt. In certain embodiments, the molar ratio of theligand of Formula (A) to the transition metal salt is about 2:1. Incertain embodiments, the molar ratio of the macromer of Formula (B) or(C) to the transition metal salt is about 1:1.

A suitable condition may also include a suitable temperature under whicha step of a method of preparing a nanostructure, supramolecular complex,or composition (e.g., gel) described herein is performed. In certainembodiments, the suitable temperature is at least about 20° C., at leastabout 40° C., at least about 60° C., at least about 70° C., at leastabout 80° C., at least about 100° C., at least about 120° C., or atleast about 140° C. In certain embodiments, the suitable temperature isnot more than about 140° C., not more than about 120° C., not more thanabout 100° C., not more than about 80° C., not more than about 70° C.,not more than about 60° C., not more than about 40° C., or not more thanabout 20° C. Combinations of the above-referenced ranges (e.g., betweenabout 20° C. and about 120° C., inclusive) are also within the scope ofthe disclosure. In certain embodiments, the suitable temperature isbetween about 20° C. and about 30° C., inclusive. In certainembodiments, the suitable temperature is about 23° C. In certainembodiments, the suitable temperature is between about 60° C. and about80° C., inclusive. In certain embodiments, the suitable temperature isabout 70° C. In certain embodiments, the suitable temperature is about80° C. In certain embodiments, the suitable temperature is about 120° C.A suitable temperature may be a variable temperature (e.g., from 20° C.to about 70° C.) during a step of a method described herein.

A suitable condition may also include a suitable pressure under which astep of a method described herein is performed. In certain embodiments,the suitable pressure is about 1 atmosphere.

A suitable condition may also include a suitable atmosphere under whicha step of a method described herein is performed. In certainembodiments, the suitable atmosphere is air. In certain embodiments, thesuitable atmosphere is an inert atmosphere. In certain embodiments, thesuitable atmosphere is a nitrogen or argon atmosphere.

A suitable condition may also include a suitable time duration that astep of a method described herein lasts. In certain embodiments, thesuitable time duration is in the order of minutes (e.g., about 30minutes), hours (e.g., about 1 hour, about 2 hours, about 4 hours, about6 hours, or about 12 hours), or days (e.g., about 1 day, 2 days, or 3days). In certain embodiments, the suitable time duration is betweenabout 12 hours to about 2 days, inclusive (e.g., about 1 day).

The nanostructures, supramolecular complexes, and compositions (e.g.,gels) prepared by the methods described herein may be isolated and/orpurified using methods known in the art, such as chromatography (e.g.,normal phase chromatography (e.g., silica gel flash chromatography),reverse phase chromatography (e.g., high performance liquidchromatography (HPLC)), precipitation, decanting, filtration,centrifuge, trituration, crystallization, recrystallization,liquid-liquid phase separation, evaporation, and drying.

Another aspect of the present disclosure relates to nanostructures,supramolecular complexes, and compositions (e.g., gels) prepared by amethod described herein. In certain embodiments, described herein aresupramolecular complexes prepared by Method B, wherein the macromer isof Formula (B-1), (B-2), (B-3), or (B-4); and optionally the transitionmetal salt is a Pd(II) salt (e.g., Pd(NO₃)₂), Ni(II) salt (e.g.,Ni(ClO₄)₂), Fe(II) salt (e.g., Fe(ClO₄)₂), or a solvate or hydratethereof, and optionally the molar ratio of the macromer to thetransition metal salt is about 1:1. In certain embodiments, describedherein are supramolecular complexes prepared by Method B, wherein themacromer is of Formula (C-1) or (C-2); and optionally the transitionmetal salt is a Pd(II) salt (e.g., Pd(NO₃)₂), Ni(II) salt (e.g.,Ni(ClO₄)₂), Fe(II) salt (e.g., Fe(ClO₄)₂), or a solvate or hydratethereof; and optionally the molar ratio of the macromer to thetransition metal salt is about 1:1.

In certain embodiments, described herein are gels prepared by Method C.In certain embodiments, the gel is a gel prepared by method C, whereinthe macromer is of Formula (B-1), (B-2), (B-3), or (B-4); and optionallythe transition metal salt is a Pd(II) salt (e.g., Pd(NO₃)₂), Ni(II) salt(e.g., Ni(ClO₄)₂), Fe(II) salt (e.g., Fe(ClO₄)₂), or a solvate orhydrate thereof; and optionally the molar ratio of the macromer to thetransition metal salt is about 1:1; and optionally the fluid is water,DMSO, acetonitrile, or a mixture thereof (e.g., an about 1:1 (v:v)mixture of water and acetonitrile); and optionally the concentration ofthe macromer is between about 5 and about 500 millimoles per liter ofthe fluid (e.g., between about 5 and about 100 millimoles per liter ofthe fluid), inclusive; and optionally the step of complexing isperformed at a temperature of between about 20° C. and about 100° C.(e.g., between about 20° C. and about 80° C.), inclusive.

In certain embodiments, the gel is a gel prepared by method C, whereinthe macromer is of Formula (B-1); and optionally the transition metalsalt is a Pd(II) salt (e.g., Pd(NO₃)₂, [(MeCN)₄Pd²⁺](BF₄ ⁻)₂, or aPd(II) salt that is not Pd(OAc)₂), a Ni(II) salt, or a solvate orhydrate thereof; and optionally the molar ratio of the macromer to thetransition metal salt is about 1:1; and optionally the fluid is DMSO,water, acetonitrile, or a mixture thereof and optionally theconcentration of the macromer is at least 5 millimoles per liter of thefluid (e.g., between 5 and 100 millimoles per liter of the fluid,inclusive; or between 15 and 100 millimoles per liter of the fluid,inclusive); and optionally the step of complexing is performed at atemperature of between 60° C. and 80° C., inclusive (e.g., about 70°C.).

In certain embodiments, the gel is a gel prepared by method C, whereinthe macromer is of Formula (B-2); and optionally the transition metalsalt is a Pd(II) salt (e.g., Pd(NO₃)₂, [(MeCN)₄Pd²⁺](BF₄ ⁻)₂, or aPd(II) salt that is not Pd(OAc)₂), a Ni(II) salt, or a solvate orhydrate thereof; and optionally the molar ratio of the macromer to thetransition metal salt is about 1:1; and optionally the fluid is DMSO,water, acetonitrile, or a mixture thereof; and optionally theconcentration of the macromer is at least 5 millimoles per liter of thefluid (e.g., between 5 and 100 millimoles per liter of the fluid,inclusive; or between 15 and 100 millimoles per liter of the fluid,inclusive); and optionally the step of complexing is performed at atemperature of between 60° C. and 80° C., inclusive (e.g., about 70°C.).

In certain embodiments, the gel is a gel prepared by method C, whereinthe macromer is of Formula (B-3); and optionally the transition metalsalt is a Pd(II) salt (e.g., Pd(NO₃)₂), or a solvate or hydrate thereof,and optionally the molar ratio of the macromer to the transition metalsalt is about 1:1; and optionally the fluid is water, and optionally theconcentration of the macromer is at least 14 millimoles per liter of thefluid (e.g., between 14 and 100 millimoles per liter of the fluid,inclusive); and optionally the step of complexing is performed at atemperature of between 20° C. and 30° C., inclusive (e.g., about 23°C.).

In certain embodiments, the gel is a gel prepared by method C, whereinthe macromer is of Formula (B-4); and optionally the transition metalsalt is a Pd(II) salt (e.g., Pd(NO₃)₂), or a solvate or hydrate thereof;and optionally the molar ratio of the macromer to the transition metalsalt is about 1:1; and optionally the fluid is water, and optionally theconcentration of the macromer is at least 9.5 millimoles per liter ofthe fluid (e.g., between 9.5 and 100 millimoles per liter of the fluid,inclusive); and optionally the step of complexing is performed at atemperature of between 20° C. and 30° C., inclusive (e.g., about 23°C.).

In certain embodiments, the gel is a gel prepared by method C, whereinthe macromer is of Formula (B-4); and optionally the transition metalsalt is a Pd(II) salt (e.g., Pd(NO₃)₂), or a solvate or hydrate thereof;and optionally the molar ratio of the macromer to the transition metalsalt is about 1:1; and optionally the fluid is water, and optionally theconcentration of the macromer is at least 9.5 millimoles per liter ofthe fluid (e.g., between 9.5 and 100 millimoles per liter of the fluid,inclusive); and optionally the step of complexing is performed at atemperature of between 60° C. and 80° C., inclusive (e.g., about 70°C.).

In certain embodiments, the gel is a gel prepared by method C, whereinthe macromer is of Formula (C-1) or (C-2); and optionally the transitionmetal salt is a Pd(II) salt (e.g., Pd(NO₃)₂), Ni(II) salt (e.g.,Ni(ClO₄)₂), Fe(II) salt (e.g., Fe(ClO₄)₂), or a solvate or hydratethereof; and optionally the molar ratio of the macromer to thetransition metal salt is about 1:1; and optionally the fluid is water,DMSO, acetonitrile, or a mixture thereof (e.g., an about 1:1 (v:v)mixture of water and acetonitrile); and optionally the concentration ofthe macromer is between about 5 and about 500 millimoles per liter ofthe fluid (e.g., between about 10 and about 100 millimoles per liter ofthe fluid), inclusive; and optionally the step of complexing isperformed at a temperature of between about 40° C. and about 100° C.(e.g., between about 60° C. and about 80° C.), inclusive.

In certain embodiments, the gel is a gel prepared by method C, whereinthe macromer is of Formula (C-1); and optionally the transition metalsalt is a Ni(II) salt (e.g., Ni(ClO₄)₂), or a solvate or hydratethereof; and optionally the molar ratio of the macromer to thetransition metal salt is about 1:1; and optionally the fluid isacetonitrile; and optionally the concentration of the macromer is atleast 10 millimoles per liter of the fluid (e.g., between about 10 andabout 100 millimoles per liter of the fluid), inclusive; and optionallythe step of complexing is performed at a temperature of between about20° C. and about 30° C., inclusive (e.g., about room temperature).

In certain embodiments, the gel is a gel prepared by method C, whereinthe macromer is of Formula (C-1) or (C-2); and optionally the transitionmetal salt is a Ni(II) salt (e.g., Ni(ClO₄)₂), Fe(II) salt (e.g.,Fe(ClO₄)₂), or a solvate or hydrate thereof; and optionally the molarratio of the macromer to the transition metal salt is about 1:1; andoptionally the fluid is acetonitrile.

In certain embodiments, the gel is a gel prepared by method C, whereinthe macromer is of Formula (C-1) or (C-2); and optionally the transitionmetal salt is a Ni(II) salt (e.g., Ni(ClO₄)₂), Fe(II) salt (e.g.,Fe(ClO₄)₂), or a solvate or hydrate thereof; and optionally the molarratio of the macromer to the transition metal salt is about 1:1; andoptionally the fluid is an about 1:1 (v:v) mixture of water andacetonitrile.

In certain embodiments, described herein are gels prepared by Method C,wherein the step of complexing of Method C further comprises thepresence of an agent (e.g., a small molecule, such as an anticanceragent (e.g., doxorubicin)). The nanostructures, supramolecularcomplexes, and gels described herein may also be modified to covalentlyattach to a -linker- agent moiety, and the resulting modifiednanostructures, supramolecular complexes, and gels are also within thescope of the present disclosure. In certain embodiments, the linker is adiradical of a peptide (e.g., a peptide of not more than 5, not morethan 10, not more than 30, or not more than 100 amino acid residues). Incertain embodiments, the linker is biodegradable. In certainembodiments, the linker is cleavable by an enzyme under physiologicalconditions. In certain embodiments, the linker is -Ile-Phe-Gly-. Incertain embodiments, the agent is a monoradical of a pharmaceuticalagent (e.g., therapeutic agent or diagnostic agent). In certainembodiments, the pharmaceutical agent is an pharmaceutical agentapproved by the FDA for use in a human or animal.

Methods of Treatment and Uses

One of the major problems in the development of formulations ofpharmaceutical agents (e.g., anti-cancer agents) is the delivery of thepharmaceutical agents with adequately high bioavailability fortherapeutic intentions. Using conventional delivery techniques, manypharmaceutical agents cannot be delivered effectively to the targettissues or target cells. Gels, such as hydrogels, have emerged as animportant class of materials for biomedical applications due to theirunique properties that bridge the gap between solid and liquid states.The gels described herein are advantageous over conventional gels thattypically include a covalently cross-linked polymer network at leastbecause the molecular network of a gel described herein is formed atleast by non-covalent interactions, such as complexation of a ligand anda transition metal ion, and thus is thermoreversible, able to flow(e.g., under a high shear stress), and able to self-heal when damaged.An agent may be encapsulated in a gel described herein (e.g.,encapsulated in a nanostructure moiety of a supramolecular complex ofthe gel) and is delivered to a tissue or cell (e.g., a target tissue ortarget cell). The gel may dissociate in the tissue or cell to releasethe agent to the tissue or cell. In certain embodiments, a nanostructuremoiety of a supramolecular complex of the gel dissociates (e.g., bybreaking the coordination bonds between (1) the ligands of Formula (A)or macromers of Formula (B) or (C) and (2) the transition metal ions,and optionally by breaking divalent linkers Y by, e.g., hydrolysis) torelease the agent that was encapsulated in the nanostructure moietybefore the dissociation. The gels described herein are also advantageousover conventional nanoparticles at least because the gels describedherein are more robust and has higher storage modulus than theconventional nanoparticles.

In another aspect, the present disclosure provides methods of deliveringan agent described herein (e.g., small molecule) to a subject, tissue,or cell. In certain embodiments, described herein are methods ofdelivering the agent to a target tissue or target cell described herein.In certain embodiments, described herein are methods of selectivelydelivering the agent to a target tissue, compared to a non-targettissue. In certain embodiments, described herein are methods ofselectively delivering the agent to a target cell, compared to anon-target cell. In certain embodiments, the agent is delivered into thesubject, tissue, or cell by the methods described herein. In certainembodiments, the agent is selectively delivered into the target tissueor target cell by the methods described herein, compared to a non-targettissue or non-target cell, respectively.

Another aspect of the present disclosure relates to methods ofincreasing the delivery of an agent to a subject, tissue, or cell. Incertain embodiments, the delivery of the agent to the subject, tissue,or cell is increased by a method described herein. In certainembodiments, the delivery of the agent to the subject, tissue, or cellby a method described herein is increased compared to the delivery ofthe agent to the subject, tissue, or cell by a control method that doesnot involve a composition described herein.

In another aspect, the present disclosure provides methods of treating adisease described herein in a subject in need thereof.

In another aspect, the present disclosure provides methods of preventinga disease described herein in a subject in need thereof.

In certain embodiments, a disease described herein is a genetic disease.In certain embodiments, the disease is a proliferative disease. Incertain embodiments, the disease is cancer. In certain embodiments, thedisease is a benign neoplasm. In certain embodiments, the disease ispathological angiogenesis. In certain embodiments, the disease is aninflammatory disease. In certain embodiments, the disease is anautoimmune disease. In certain embodiments, the disease is ahematological disease. In certain embodiments, the disease is aneurological disease. In certain embodiments, the disease is agastrointestinal disease. In certain embodiments, the disease is a liverdisease. In certain embodiments, the disease is a spleen disease. Incertain embodiments, the disease is a respiratory disease. In certainembodiments, the disease is a lung disease. In certain embodiments, thedisease is a painful condition. In certain embodiments, the painfulcondition is inflammatory pain. In certain embodiments, the painfulcondition is associated with an inflammatory disorder and/or anautoimmune disorder. In certain embodiments, the disease is agenitourinary disease. In certain embodiments, the disease is amusculoskeletal condition. In certain embodiments, the disease is aninfectious disease. In certain embodiments, the disease is a psychiatricdisorder. In certain embodiments, the disease is a metabolic disorder.In certain embodiments, the disease is hepatic carcinoma. In certainembodiments, the disease is hypercholesterolemia. In certainembodiments, the disease is refractory anemia. In certain embodiments,the disease is familial amyloid neuropathy.

Another aspect of the present disclosure relates to methods ofgenetically engineering a subject. In certain embodiments, the subjectis genetically engineered to increase the growth of the subject. Incertain embodiments, the subject is genetically engineered to increasethe subject's resistance to pathogenic organisms and/or microorganisms(e.g., viruses, bacteria, fungi, protozoa, and parasites).

In certain embodiments, a method described herein includes administeringto the subject a composition described herein. In certain embodiments, amethod described herein includes administering to the subject aneffective amount of a composition described herein.

In certain embodiments, a method described herein includes contactingthe tissue with a composition described herein. In certain embodiments,a method described herein includes contacting the tissue with aneffective amount of a composition described herein.

In certain embodiments, a method described herein includes contactingthe cell with a composition described herein. In certain embodiments, amethod described herein includes contacting the cell with an effectiveamount of a composition described herein.

In certain embodiments, a subject described herein is a human. Incertain embodiments, the subject is an animal. In certain embodiments,the subject is a non-human animal. The animal may be of either sex andmay be at any stage of development. In certain embodiments, the subjectis a fish. In certain embodiments, the subject is a mammal. In certainembodiments, the subject is a non-human mammal. In certain embodiments,the subject is a domesticated animal, such as a dog, cat, cow, pig,horse, sheep, or goat. In certain embodiments, the subject is acompanion animal such as a dog or cat. In certain embodiments, thesubject is a livestock animal such as a cow, pig, horse, sheep, or goat.In certain embodiments, the subject is a zoo animal. In anotherembodiment, the subject is a research animal such as a rodent (e.g.,mouse, rat), dog, pig, or non-human primate. In certain embodiments, theanimal is a genetically engineered animal. In certain embodiments, theanimal is a transgenic animal. In certain embodiments, the subject is ahuman with a disease described herein. In certain embodiments, thesubject is a human suspected of having a disease described. In certainembodiments, the subject is a human at risk of developing a diseasedescribed herein.

In certain embodiments, a cell described herein is in vivo. In certainembodiments, a cell described herein is in vitro.

Another aspect of the present disclosure relates to uses of ananostructure described herein in a method described herein (e.g., usesfor delivering an agent to a subject, tissue, or cell; uses for treatinga disease in a subject in need thereof; and uses for preventing adisease in a subject).

Another aspect of the present disclosure relates to uses of asupramolecular complex described herein in a method described herein(e.g., uses for delivering an agent to a subject, tissue, or cell; usesfor treating a disease in a subject in need thereof; and uses forpreventing a disease in a subject).

Another aspect of the present disclosure relates to uses of acomposition (e.g., gel) described herein in a method described herein(e.g., uses for delivering an agent to a subject, tissue, or cell; usesfor treating a disease in a subject in need thereof; and uses forpreventing a disease in a subject).

EXAMPLES

In order that the invention described herein may be more fullyunderstood, the following examples are set forth. The synthetic andbiological examples described in this application are offered toillustrate the nanostructures, supramolecular complexes, pharmaceuticalcompositions, and methods provided herein and are not to be construed inany way as limiting their scope.

Preparation of the Nanostructures, Supramolecular Complexes, andCompositions (e.g., Gels)

The nanostructures, supramolecular complexes, and compositions (e.g.,gels) described herein can be prepared from readily available startingmaterials using the following general methods and procedures (e.g., themethods shown in any one of Schemes 1 to 4). It will be appreciated thatwhere typical or preferred process conditions (i.e., reactiontemperatures, times, mole ratios of reactants, solvents, pressures,etc.) are given, other process conditions can also be used unlessotherwise stated. Optimum reaction conditions may vary with theparticular reactants or solvents used, but such conditions can bedetermined by those skilled in the art by routine optimization.

In Scheme 1, each instance of U is independently an organoboron moiety(e.g., —B(OH)₂, a borate moiety

and each instance of V^(A) and V^(B) is independently halogen (e.g., Cl,Br, or I) or —OTf.

Example 1. Preparation and Characterization of Ligand B-1

In an exemplary set of experiments, diacids

such as

were synthesized according to the method shown in Scheme 5 (see, e.g.,U.S. Pat. No. 8,067,505), wherein the number-average molecular weight(M_(n)) of the PEG moiety

was about 2 kDa, 4.6 kDa, 6 kDa, 10 kDa, 25 kDa, and 35 kDa. The yieldswere at least about 80%.

In an exemplary set of experiments, diacid

was synthesized according to the method shown in Scheme 6 in a 92.4%yield, and the product was pure by ¹H NMR and mass spectroscopy(MALDI-TOF).

In an exemplary set of experiments, telechelic bromo-poly(n-butylacrylate) (telechelic bromo-pNBA) with a M_(n) of 4.2 kDa (degree ofpolymerization (DP) was about 30; and polydispersity (PDI) was about1.13 as determined by GPC) or 13.9 kDa (DP was about 106); and PDI wasabout 1.08 as determined by GPC).

In an exemplary set of experiments, ligand B-1 was prepared according tothe method shown in Scheme 7. An exemplary ¹H NMR spectrum (DMSO-d₆, 400MHz) is shown in FIG. 12.

Example 2. Preparation and Characterization of Nanosphere I-1

In an exemplary set of experiments, nanosphere I-1 was preparedaccording to the method in Scheme 3, steps (b-1) and (b-2), wherein theligand of Formula (A) was ligand A-1, and the Pd(II) salt was Pd(NO₃)₂.To a 2-mL vial with A-1 (13.13 mg, 0.05006 mmol) dissolved in 366.7 μLof DMSO-d₆ was added via micropipette a solution of Pd(NO₃)₂.2H₂O (6.67mg, 0.02503 mmol) in 133.3 μL of DMSO-d₆. The head-space of the vial wasbriefly purged with argon, the vial was closed with a screw-cap, and theresultant mixture was immediately vortexed, giving rise to alight-yellow liquid with small gelatinous pieces dispersed in it. Themixture was heated at 70° C. for 8 h, during the course of which, itbecame a light yellow homogeneous solution. A liquid was formed, whichcontained predominantly one supramolecular species. An exemplary ¹H NMRspectrum (DMSO-d₆) of the resulting nanosphere I-1 evidenced theformation of nanospheres. Exemplary MTT proliferation assay results ofnanosphere I-1 using HeLa cells are shown in FIG. 14, which indicatethat nanosphere I-1 was toxic to HeLa cells with an IC₅₀ of 7.9 μM.

Example 3. Preparation and Characterization of Supramolecular Complexesand Gels

In another exemplary set of experiments, supramolecular complexes andgels were prepared according to the method of FIG. 1A. The formation ofthe supramolecular complexes and gels were evidenced by ¹H NMR (FIG.1C). Gelation was virtually instantaneous at the sites where thereactants came into contact. After the reaction mixture was heated at70° C. for 8 hours or 80° C. for 4 hours, it became homogeneous. Whenligand B-2 and Pd(NO₃)₂ were combined at a concentration of 0.01 M witha 15% excess of ligand B-2, the reaction mixture became a homogeneousliquid after heating at 100° C. overnight; the ¹H NMR spectrum of theresulting mixture suggested formation of nanospheres. The rate ofgelation can be tuned by adjusting the reactivity of the transitionmetal (e.g., Pd(II)) salt. In some cases, the more labile the counterionof the transition metal salt, the more rapid the gelation is. Pd(NO₃)₂and [(MeCN)₄Pd²⁺](BF₄ ⁻)₂ resulted in rapid gelation, while no gelationwas observed seen when Pd(OAc)₂ was used. In some cases, the counterionof the transition metal salt is a non-coordinating counterion. In somecases, the counterion of the transition metal salt provides a sufficientkinetic barrier to reduce the rate of gelation. For instance, is wasobserved that 3-chloropyridine can be used as such an auxiliary ligandsthat can be used with a Pd(II) salt. See, e.g., Scheme 3. From thefrequency sweeps spanning 0.1 and 100 rad/s, shortly after mixing of allthe reaction components, a storage modulus G′ of about 16-21 kPa and aabout 15-fold lower G″ (0.74-1.4 kPa) were observed (FIGS. 21A and 5B),confirming that the observed gelation had, indeed, taken place. Duringthe subsequent heating stage at 70° C., G′ dropped, reaching a plateauafter 5 hours at 8.8-11 kPa; G″, on the other hand, increased to 3.7-5.5kPa. Thus, the reaction mixture remained a gel, but it lost asignificant amount of elasticity and became more liquid-like. Theseobservations are consistent with the hypothesis that upon mixing ligandB-2 and Pd(NO₃)₂, a largely random network is formed, and during theheating stage, this network transformed to linked nanospheres throughreversible coordination of the Pd(II) ions with the nitrogen atomslabeled with 1′ and 1″ of the pyridinyl moieties. Because of the smallsize of the PEG2000 divalent linkers and the relatively large size ofthe nanospheres, as well as the fact that there were 24 PEG2000 divalentlinkers extending from each nanosphere, it may be very difficult to haveeach chain link two different nanospheres. Thus, loopy nanospheres mayhave formed, which led to a reduced G′ and elevated G″.

In another exemplary set of experiments, supramolecular complexes andgels were prepared according to the method of FIG. 2C, where theconcentration of ligand B-2 in DMSO-d₆ was 0.025 M. The reaction(gelation) was monitored by measuring the rheology (e.g., shear storagemodulus and shear loss modulus) of the reaction mixture using equipmentshown in FIG. 2B. The results were shown in FIG. 2A, where the shearrate was 10 rad/s, and the reaction temperature was 70° during theduration of the experiment. The results of the reaction mixture at 70°C. were fitted to exponential curves.

In another exemplary set of experiments, supramolecular complexes andgels were prepared according to the method of FIG. 1A, wherein thereaction temperature and time duration were according to FIGS. 3A and3B. The formation of the supramolecular complexes and gels wereevidenced by ¹H NMR (FIGS. 3A and 3B).

In another exemplary set of experiments, supramolecular complexes andgels were prepared according to the method of FIG. 1A, wherein theconcentration of ligand B-2 were as provided in FIGS. 4A and 4B, and thereaction temperature was room temperature (FIG. 4A) and 70° C. (FIG.4B). Also shown in FIGS. 4A and 4B are images of the reaction mixtures,which indicate that reaction mixtures containing 15 mM or 25 mM ofligand B-2 in DMSO-d₆ were able to form gels, whereas reaction mixturescontaining 10 mM or 5 mM of ligand B-2 in DMSO-d₆ were not able to formgels. FIG. 4C shows the rheology of gels formed from differentconcentrations of ligand B-2.

In another exemplary set of experiments, supramolecular complexes andgels were prepared according to the method of FIG. 1A, wherein ligandB-2 was partially replaced with ligand A-1, wherein the mole amount ofligand A-1 was twice the mole amount of ligand B-2 that was replaced byligand A-1. Exemplary modulus and shear viscosity results are shown inFIGS. 5B and 5C. Even replacement of 80% of ligand B-2 with 2equivalents of ligand A-1, a gel was still formed.

In another exemplary set of experiments, supramolecular complexes andgels were prepared according to the method in Scheme 4, wherein thePd(II) salt was Pd(NO₃)₂, and the concentration of ligand B-1 in DMSOwas 5 mM (gel III-5), 10 mM (gel III-6), or 100 mM (gels III-1 toIII-4). Exemplary ¹H NMR spectra are shown in FIG. 9A (gel III-5) to 9B(gel III-6). Differential scanning calorimetry (DSC) experiments wereperformed on the gels prepared from 100 mM solutions. The reactionmixtures were quenched at 0 min (gel III-1), 2.5 h (gel III-2), 5.5 h(gel III-3), and 8.5 h (gel III-4), respectively, by addition of diethylether to the reaction mixtures to extract DMSO and provide a poorsolvent. The DSC graphs showed a melting transition for gel III-1 atabout 40° C., corresponding to PEG melting. No melting transition wasobserved for gels III-2 to III-4. The gels (gel III-5) obtained from a 5mM solution was dialyzed against water (2×700 mL). The gels all turnedfrom purple to orange upon addition of an aqueous solution of Ni(ClO₄)₂.Similar results were obtained when B-2 was used instead of B-1.

In another exemplary set of experiments, supramolecular complexes andgels were prepared according to the method in FIG. 15A. Theconcentration of ligand C-1 in acetonitrile was 10 mM. Initial rheologymeasurements indicated that gelation was completed within seconds.Oscillatory rheology measurements in a frequency sweep from 0.1-628rad/s over 100 minutes showed that G′ had already crossed G″ before thefirst measurement (FIG. 15B). After mixing all the reactants andreagents, a storage modulus was measured to be close to 1×10⁶ Pa, and aloss modulus was measured to be 1×10⁵ Pa, which are high moduli fornetworks whose junctions are presumably dynamic. The increase in G′ andG″ after 43.9 minutes may be attributed to evaporation of the solvent.The supramolecular complexes and gels may be formed through junctionself-assembly as shown in FIG. 15C. The gelation as indicated by theshear viscosity of the reaction mixture over reaction time is shown inFIG. 11A. FIG. 11A indicates that the gel formed at different rates fordifferent solvents (immediately for MeCN and after about 2 hrs forwater). The frequency sweep as indicated by a plot of shear storagemodulus (G′) and shear loss modulus (G″) of the gel versus the strain(ω) is shown in FIG. 11B. FIGS. 11A and 11B indicate that the differentsolvents affected the kinetics of the gel formation (e.g., the kineticsof forming the secondary structure of the gel) but did not show a cleareffect on the frequency behavior of the gel.

In another exemplary set of experiments, supramolecular complexes orgels were not formed using the method in Scheme 4, wherein the Pd(II)salt was replaced with a Zn(II) salt (e.g., Zn(ClO₄)₂), and the molarratio of ligand B-1 or B-2 to the Zn(II) salt was 2:1 or 3:1.

Example 4. Preparation and Characterization of Loopy Nanospheres

In another exemplary set of experiments, loopy nanospheres were preparedaccording to the method in FIG. 13A, wherein the concentration of ligandB-1 in DMSO-d₆ was below 10 mM. The formation of loopy nanospheres wasevidenced by ¹H NMR and DLS results (FIG. 13B). The average diameter Dhof the PEG moieties of ligands B-1 was about 2.5 nm, and the averagediameter of the nanosphere without the PEG moieties was about 2.8 nm.

Example 5. Preparation and Characterization of Supramolecular Complexesand Gels, Each of which Contained Doxorubicin

Bright red supramolecular complexes and gels were formed by heating inDMSO-d₆ at 70° C. for 1 day a solution of ligand B-2 (100 mM) andPd(NO₃)₂.H₂O in the presence of doxorubicin (100 mM). An image of theresulting gel is shown in FIG. 6B. The gel of FIG. 6B four times withDMSO-d₆ (4×300 mL) an image of the gel after the extractions is shown inFIG. 6C, and images of the four extracts are shown in FIG. 6D.Unencapsulated doxorubicin was removed by extraction with fresh DMSO-d₆,leaving a light-red gel with encapsulated doxorubicin. While the colorof the first DMSO-d₆ extract was bright red, the subsequent extracts hadvirtually identical faint-orange color, indicating that an approximatelyconstant low level of doxorubicin was released each time after the firstwash. This observation is consistent with expected encapsulation andsubsequent slow release of the doxorubicin from the nanospheres in theformed supramolecular complexes and gels.

Example 6. Solution Assembly of Ligands L1 and L2

Prior to the formation of suprametallogels, it was first sought toconfirm that L1 and L2 form the expected Pd₁₂L₂₄ and Pd₂L₄ assemblies,respectively. Exposure of L1 to Pd(NO₃)₂. 2H₂O in DMSO-d⁶ (0.100 M)initially provided a gelatinous mixture characterized by highlybroadened downfield-shifted peaks in the ¹H NMR spectrum (FIG. 17A).This mixture transformed into a clear light-yellow solution upon heatingfor 8 h at 70° C. The ¹H NMR spectrum of this solution contained one setof broad ligand-based resonances consistent with a highly symmetricnanoscopic assembly (FIG. 17A); the resonances in the aromatic regionwere shifted downfield compared to those of L1, and the correspondingchemical shifts were virtually identical to those reported previously byFujita and coworkers for methanofullerene-functionalized spheresconstructed from the same ligand.⁵⁰

Likewise, upon mixing L2 with Pd(NO₃)₂.2H₂O in DMSO-d⁶ (0.100 M), amixture of different L2-Pd²⁺ species was obtained as gathered from thepresence of many sets of ligand-based resonances in the aromatic regionof the ¹H NMR spectrum (FIG. 17B). Remarkably, upon annealing for 2 h at70° C., this mixture coalesced into a single highly symmetric smallassembly, as inferred from the single set of slightly broadenedligand-based resonances in the ¹H NMR spectrum (FIG. 17B). Annealing for8 h at 100° C. afforded an identical spectrum, implying that theassembly is stable under these conditions. Fourier transform ioncyclotron resonance (FT-ICR) electron spray ionization mass spectrometry(ESI-MS) exhibited a dominant species with mass/charge (m/z)corresponding to the triply cationic paddlewheel mono-nitrate. X-raycrystallography confirmed the M₂L₄ paddlewheel connectivity of thisassembly (FIG. 17C).⁶⁹ Considered collectively, these data confirm thatboth L1 and L2 initially form complex mixtures of assemblies uponexposure to Pd(NO₃)₂.2H₂O in DMSO-d⁶ at room temperature, and that thesemixtures quantitatively convert to well-defined assemblies underthermodynamic control.

Example 7. Preparation of Suprametallogels Using (1) B-3 or B-4 and (2)Pd(NO₃)₂.2H₂O; and Annealing Experiments of the Suprametallogels

L1 and L2 were coupled onto the ends of carboxylic acid terminated 2.2kDa polyethylene glycol (PEG) to generate macromers B-3 and B-4,respectively (FIG. 16C). Exposure of B-3 to Pd(NO₃)₂.2H₂O at in DMSO-d₆23° C. resulted in immediate gelation when [Pd²⁺]=[B-3]≥14 mM (0.043g/mL). Macromer B-4 formed gels at all concentrations tested above 9.5mM (0.026 g/mL).

In an exemplary preparation, to a 1-dram scintillation vial was added20.25 mg (7.5 μmol) of macromer (B-3 or B-4) and then 210.0 μL DMSO-d⁶.In a 2-mL scintillation vial, a stock solution of Pd(NO₃)₂.2H₂O inDMSO-d⁶ was prepared at a concentration of 11.1 mg Pd(NO₃)₂.2H₂O per1.00 mL DMSO-d⁶ (after vortexing for ˜1 min, a clear orange solutionforms). 90 μL of this solution was transferred via micropipette to thesolution of the macromer, and gelation was observed immediately,although the gel coloration is inhomogeneous. The headspace of the vialis briefly purged with argon, the vial is sealed, and heated at 80° C.for 4 h to give rise to a homogeneous light-yellow gel (translucent ifderived from B-4, opaque if derived from B-3). Molarity of macromer inthe gel (in this case 24 mM) was determined by dividing the number ofmoles of the macromer used by the total volume of the gel, accountingfor the non-negligible contribution of the polymer to the total volume.

The observation that the paddlewheel-former B-4 gels at a significantlylower concentration compared to B-3 suggests that that even upon initialmixing, gels derived from B-3 and B-4 have fundamentally differentnetwork structures despite their identical composition.

Based on the solution assembly studies described above, it was expectedthat gels formed upon immediate mixing of B-3 or B-4 and Pd²⁺ at roomtemperature are crosslinked through a complex mixture of branchedcoordination polymers rather than the well-defined target assemblies.Thus, these gels were annealed under conditions similar to those used toinduce self-assembly of the free ligands. The annealing process wasmonitored by variable temperature ¹H solid state NMR (VT ¹H ssNMR)spectroscopy (FIGS. 18 and 19). In the case of paddlewheel-former B-4,the spectra revealed a transformation similar to that observed for freeligand L2: prior to annealing there were multiple sets of ligand-derivedresonances in the ¹H ssNMR spectrum, which coalesced and sharpened intosingle resonances that mapped closely onto the solution ¹H NMR spectrumof the L2-based paddlewheels. These data suggest that the networkjunctions are converted into symmetric, paddlewheel structures within 1h at 70° C.

In the case of gels prepared from macromer B-3, structural changes uponthermal annealing by ssNMR could not be resolved due to significant peakbroadening (FIG. 19B). However, the peaks of these resonances have thesame chemical shifts as those observed in solution ¹H NMR spectra ofspheres formed from free L1 after annealing (FIG. 17A) and also soluble,nanoscale coordination polymers formed from mixing B-3 with Pd²⁺ at veryhigh dilution followed by annealing (FIG. 19A, inset cryo-TEM imageshows nanoscale coordination polymers of B-3 and Pd²⁺ formed at highdilution). Nevertheless, while the self-assembly of M₁₂L₂₄ cage-likejunctions may occur in these gels,⁷⁰ this cannot be confirmedconclusively from ssNMR. Branched assemblies, which may consist ofsphere fragments or larger (>24 ligand) clusters, could lead to similarssNMR spectra. Regardless, these data clearly demonstrate that thechoice of meta-versus para-pyridine ligands gives rise to networks withsignificantly different structure.

Example 8. Simulations of Assembly and Gelation Processes

To gain deeper insight into the impact of ligand identity on networkassembly, it was turned to computer simulation (FIGS. 20A and 16B). Ourapproach extended the molecular dynamics simulations of Yoneya andFujita^(71,72) in which the details of metal-ligand binding werecaptured empirically through Coulombic interactions, and mediated by animplicit solvent. This model⁷¹ have been adapted to include themeta-substituted version of the bis-pyridine ligand and the ability tosimulate the case where individual pairs of ligands are attached to eachother via a long flexible polymer chain. Our scheme for generatingtrajectories, which was chosen to mimic the sudden introduction of Pd²⁺into a well-mixed solution of ligands, involved propagating a randomlydistributed mixture of metal ions and ligand molecules underexperimental conditions (e.g., temperature and concentration). Asillustrated in FIG. 20A, simulations consisted of 98 metal ions and 192bis-pyridine ligand molecules (or 96 ligand-terminated macromers) in aperiodically replicated cubic simulation box with a volume of 6540 nm³.Five different trajectory ensembles were generated corresponding to theassembly of cage-forming ligands (L-para), paddlewheel-forming ligands(L-meta), L1-terminated 2.2 kDa PEG (macromer B-3), and L2-terminated2.2 kDa PEG (macromer B-4). A more detailed description of oursimulations, which are nearly identical to those presented in Reference71,⁷¹ are presented in the supporting information. In our analysis,cluster size was refer to in terms of the number of ligands in a givenmetal-ligand cluster, denoted with the quantity y as in M_(x)L_(y). Ourparticular focus is on the relationship between ligand identity (i.e.,meta- or para-substituted bis-pyridine) and metal-ligand clusterformation, how that relationship is affected by the linking of monomersby flexible polymer chains, and finally in characterizing theinter-cluster connectivity (as it relates to gelation) that accompaniesthe spontaneous assembly of tethered ligand dimers. Below, the solutionassembly of Pd²⁺ and ligand monomers are described, and thenetwork-forming consequence of linking monomers with flexible polymerchains is discussed.

Example 9. Solution Assembly of Free Ligands L-Para and L-Meta

Trajectories initialized with randomly distributed ligand and metal ionpositions exhibit the rapid formation of relatively unstablemetal-ligand clusters followed by the slow annealing of the clustermorphology as the system evolves towards a more thermodynamicallyfavorable configuration. This behavior is illustrated in FIG. 20B, whichcontain plots of the time-dependent (over 1 μs) average cluster size,

${{\overset{\_}{y}(t)} = {\frac{1}{N(t)}{\sum\limits_{i = 1}^{N{(t)}}\;{y_{i}(t)}}}},$where the summation is taken over all of the N(t) clusters that exist attime t, and y_(i)(t) is the number of ligands present in the i^(th)cluster at time t. More specifically, the black and grey linescorrespond to the average cluster size in solutions containing L-paraand L-meta ligands, respectively. While both systems exhibit a clearseparation of timescales between initial cluster formation (t≤100 ns)and the subsequent annealing of network morphology (t≥200 ns), theaverage cluster size for the sphere-forming L-para ligand (40±20) issignificantly larger than that of the paddlewheel-forming L-meta ligands(6.3±0.5). The origin of this difference can be understood byconsidering the cluster size distributions (FIG. 20C). FIG. 20C showshistograms of the probability, P_(y), that at time t≈1 μs, a givenligand belongs to a cluster with size y. The results for thecage-forming L-para ligand (shown in black), indicate that there is nota particularly strong preference for the formation of the schematictarget M₁₂L₂₄ cluster (such as the one shown in FIG. 16B), which isconsistent with the findings of Yoneya and Fujita.⁷¹ In fact, thedistribution of cluster sizes for L-para clusters after 1 μs is broadand, for the concentration that has been considered, predicts theprevalence of very large clusters such as those shown in FIG. 20A, farleft. In stark contrast, for the paddlewheel-forming L-meta ligand P_(y)is narrowly distributed and peaked at y=4 (see FIG. 20C), whichcorresponds to the schematic target M₂L₄ paddlewheel shown in FIG. 16B.Such clusters are also readily observed in FIG. 20A, second from theleft. Taken together, these simulated results support the key notionunderlying our suprametallogel design: the geometry of L-parafacilitates the formation of large clusters while L-meta exhibits astrong preference for small M₂L₄ clusters. It should be noted, however,that it has been observed the occasional presence of system-spanningL-pra clusters, which is an indication that our results may containartifacts due to system size effects, for example in the preferentialstabilization of clusters that are large enough to interact withthemselves through the periodic boundaries of our simulation. Indeedwhen simulations were perform at lower concentration (larger simulationcell), a significantly reduced probability for the formation of large(y>60) clusters was observed. These effects, combined with our inabilityto simulate the long timescales associated with the real assemblyprocess, contribute to a lower than expected yield of M₁₂L₂₄ clustersbased on experimental observation. In fact, our simulations more likelyreflect the experimental systems prior to annealing (FIGS. 17A to 17C).

Example 10. Simulating the Assembly of Suprametallogels

To investigate suprametallogel formation, simulations were performed inwhich pairs of ligand monomers were tethered together via a modelflexible polymer chain (see FIG. 20A, right). The polymer chain wasdescribed implicitly in the form of a ligand-ligand pair potential thatexerted a bias on the relative position of bound ligands. This biaspotential, equal to the potential of mean force governing the end-to-enddistance of a three-dimensional self-avoiding random walk, was chosen tomimic details of the PEG chains used in our experiments (e.g., macromersB-3 and B-4). Similar to the free ligand simulations described above,trajectories were initiated from configurations with randomlydistributed metal ions and macromers whose end-ligands were initiallyseparated by the mean end-to-end distance of the model polymer chains.FIG. 20A shows snapshots of suprametallogels derived from macromers B-3and B-4.

The average cluster size y and the cluster size distributions P_(y) formacromers B-3 and B-4 are shown along side the free ligand results inFIGS. 20B and 20C. It was found that the qualitative difference betweeny for the para- and meta-pyridine based ligands, specifically on thetendency for para- to form a broad distribution of larger clusters andmeta- to form a narrow distribution of small clusters, is preserved uponthe addition of a flexible polymer tether. For both species, however,the presence of a polymer linker tends to favor the formation of smallerclusters (relative to the free ligands) and thereby lower y (FIG. 20B);after 1 μs networks comprised of macromers B-3 and B-4 display y values(y ₁ and y ₂, respectively) of 21±6 and 5.3±0.7. It is clear from FIG.20B, however, that the L-para based systems are not in a state ofdynamic equilibrium after 1 μs. Thus, it cannot be distinguished whetherthe decrease in average cluster size upon addition of a polymer linkeris the result of a thermodynamic shift in cluster size distribution orrather due to retardation of network relaxation. Based upon the resultsfrom L-meta based clusters, it was hypothesized that the effect iskinetic in nature, but ultimately the resolution requires longersimulations. Nonetheless, these results confirm that the assemblypreferences between para-versus meta-substituted pyridine ligandseffectively translate into suprametallogels, and corroborate the NMRresults discussed above.

Example 11. Analysis of Network Connectivity and Elastically InactiveDefects

To explain the unique mechanical properties of suprametallogels,simulations were expanded to include analysis of key network defectsthat impact bulk mechanical properties. Specifically, theinterconnectivity of metal-ligand clusters was computed, and quantifyingthe elastically inactive primary cyclic, or “loop” defects, was focusedon, that are formed when both ligand ends of a single macromer belong tothe same assembled metal-ligand cluster. For a given cluster with yligands, the quantity ρ_(L) has been computed, which is the density ofligands in that cluster that are members of loop defects. FIG. 20D showsplots of the average value of ρ_(L) as a function of cluster size formacromers B-3 and B-4. Our simulations have a finite number ofmacromers, and thus there is a trivial correlation between loop densityand cluster size that can be understood by considering clusters composedof randomly selected ligands. In this case, loop density is expected toscale linearly with cluster size between the trivial end points, ρ_(L)=0for y=1 and ρ_(L)=1 for y=192 (black curve, FIG. 20D). Insuprametallogels comprised of B-3 and B-4 it was found that loopformation increases rapidly with cluster size. Furthermore, there is aslightly greater prevalence of loops for B-3 compared to B-4. Keeping inmind that networks comprised of B-3 contain a broad range of clustersizes, including very large ones, and that networks comprised of B-4feature small, fairly uniform clusters, the data presented in FIG. 20Dprovides a critical insight: networks comprised of B-3 have a muchgreater prevalence of elastically inactive loop defects compared tonetworks comprised of B-4 (see arrows, FIG. 20D).

Example 12. Mechanical Properties of Suprametallogels

The data described above supports our initial hypothesis thatmetallosupramolecular assembly induced gelation of polymers bearingisomeric bis-pyridine ligands can provide suprametallogels withdramatically different structure based on tuning the average clustersize, e.g., branch functionality. It was next sought to assess theimpact of these structural differences on bulk suprametallogelmechanical properties. Oscillatory rheology was used to monitor thestorage and loss moduli (G′ and G″, respectively) for 6.3 wt. % gelsderived from B-3 and B-4 as a function of oscillation angular frequency(w) and strain both before and after thermal annealing.

As shown in FIGS. 21A to 21D, these gels behaved as elastic solids—theirG′ values were always larger than their G″ values—over the entire rangeof tested frequencies both before and after annealing. Thus, thesesuprametallogels do not display a viscous flow regime at low frequenciesat 25° C. Despite this similarity, other mechanical properties of thegels were strikingly different. For example, prior to thermal annealing,the high-frequency G′ of gels based on sphere-former B-3 (12±3 kPa, FIG.21A) was a factor of four greater than that of gels based onpaddlewheel-former B-4 (3.0±0.5 kPa, FIG. 21B). This observation impliesa significantly greater average elastically active junctionfunctionality, e.g., cluster size, in gels based on B-3 prior toannealing, which agrees well with our NMR and molecular dynamicssimulations.⁷³

Upon thermal annealing, a decrease was observed in the high frequency G′value for both sets of gels; the final G′ values were 5.2±0.3 kPa and1.9±0.2 kPa for suprametallogels derived from B-3 and B-4, respectively(FIGS. 21A and 21B, grey curves). Notably, this decrease is greater fornetworks derived from B-3. Our simulations show that systems based onpara-ligands initially have a broad distribution of cluster sizes withmany clusters that can be much larger than the target 24 ligands,whereas those based on meta-ligands are more narrowly distributed nearthe target 4 ligands. Thus, assuming that thermal annealing drives thesesystems towards the target cluster size (as shown in FIGS. 17 and 18),suprametallogels based on para ligands should experience a greaterdecrease in cluster size and a corresponding greater decrease in G′. Oursimulations also show that as cluster size decreases, the number ofelastically inactive loops should decrease; this effect should provide acompensatory increase in the bulk modulus. Based on our data, thecluster size effect on G′ outweighs possible changes in the loopfraction. The relationship between loop defect formation and clusterstructure in suprametallogels will provide an interesting avenue forfuture experimental and theoretical research.

Strain sweeps in oscillatory shear at 10 rad/s performed into thenonlinear regime illustrate that the bite angle of the ligand and thestate of assembly (before or after annealing) both have a significantimpact on the yield behavior of the gels (FIGS. 21C and 21D). The yieldstress of gels derived from B-4 (2,570±400 Pa, FIG. 21D) was comparableto that for suprametallogels derived from B-3 prior to annealing(2,080±840 Pa, FIG. 21C). However, while the former showed only a 28%(to 1840±140 Pa) decrease in yield stress after annealing, the latterexhibited an 87% decrease (to 260±110 Pa). Furthermore, while the yieldstrain of suprametallogels derived from B-3 exhibited a decrease from˜18% to ˜6.3% after annealing (FIG. 21C), the yield strain of gelsderived from B-4 increased after annealing from ˜83% to ˜110% (FIG.21D). Notably, suprametallogels derived from B-4 could withstand morethan 17 times as much strain as those derived from B-3. These data agreewith our picture of suprametallogel structure. Though macromer B-3provides somewhat stiffer materials due to an increase in f(5.2±0.3 kPafor B-3 versus 1.9±0.2 kPa for B-4), the presence of large clusters inthese networks and the fact that the 2.2 kDa PEG chains have roughly thesame radius as the target M₁₂L₂₄ cages lead to brittle materials; thePEG chains in networks of B-3 are either elastically inactive (inloops), or highly extended to bridge the large clusters. These extendedPEG chains cannot bear significant stress. In contrast, the PEG chainsin networks comprised of B-4 are less extended and more capable ofbearing stress. In future studies, increasing the PEG chain lengthshould facilitate enhancements in yield stress in networks build formpara-pyridine ligands.

Lastly, it was sought to assess whether networks comprised of B-3 or B-4could self-heal upon thermal annealing (FIGS. 22A to 22F). Samples ofsuprametallogels derived from B-3 (FIG. 22A) and B-4 (FIG. 22D) were cutwith a razor blade to introduce macroscopic fractures (FIGS. 22B and22E, fractures labeled with arrows). These samples were then subjectedto heating for 4 h at 80° C., and healing was assessed based onmacroscopic observation, e.g., did the two separated gel pieces becomeone uniform piece after annealing? Note that no additional solvent wasadded, and no pressure was applied to bring the two pieces into contact.Based on the collective data presented above, it was expected thatnetworks comprised of B-3 would be more difficult to heal, since healingin these materials would require complete reassembly of large clusters;loop defect shuffling within disconnected clusters could be more rapidthan inter-cluster healing. The smaller junctions in networks preparedfrom B-4 would facilitate the bridging of gaps formed during thefracture. Indeed, it was found that suprametallogels prepared from B-3were unable to heal under these conditions (FIG. 22C), while those fromB-4 completely recovered their initial state.

A major advantage of the suprametallogels described herein is theability to program nano-scale architectures within a polymeric network,which could give rise to emergent, unexpected properties. When theswelling behavior of suprametallogels comprising B-3 or B-4 wasexamined, it was surprised to find that the suprametallogels comprisingB-4 were capable of absorbing a remarkable 157±9 times their own weightin solvent (DMSO), whereas the suprametallogels comprising B-3 absorbedonly 23±2 times their own weight (FIG. 22G). The latter value (23±2) istypical for a covalent network whereas the former value (157±9) is onpar with the best superabsorbent polymers known (Chen, J., Park, H. &Park, K. Synthesis of superporous hydrogels: Hydrogels with fastswelling and superabsorbent properties. Journal of biomedical materialsresearch 44, 53-62, (1999). These observations suggest thatsuprametallogels derived from B-4 and other paddlewheel forming ligandscould have promising applications as super-absorbent materials.

Example 13. Preparation of Macromer C-2

A telechelic bis-pyridyl-tetrazine macromer (C-2) was synthesized byappending the bptz moiety on the ends of poly(ethylene glycol) (MW: 2000Da) with a carbon spacer, through modified procedures of published work(Cok, A. M.; Zhou, H.; Johnson, J. A. Macromolecular Symposia 2013, 329,108; Zhou, H.; Woo, J.; Cok, A. M.; Wang, M.; Olsen, B. D.; Johnson, J.A. Proceedings of the National Academy of Sciences 2012).

Example 14. Preparation of Gels Using (1) Macromer C-1 and (2) Ni(ClO₄)₂Hydrate or Fe(CO₄)₂ Hydrate; and Characterizations of the Gels

Mixing macromer C-1 with Ni(ClO₄)₂ hydrate or Fe(ClO₄)₂ hydrate in a 1:1metal to ligand ratio in acetonitrile (100 mg/mL of C-1 at roomtemperature) resulted in qualitatively fast formation of gels with anaccompanying color change. This observation leads to the conclusion thatthe bptz end-groups and metal ions must be aggregating in some higherorder; otherwise, the macromer would merely undergo linear extension andnot form a gel. A solution of C-1 does not gel on its own, which meansthat these gels are not merely physical gels from π-π stacking or otherinteractions.

To demonstrate that the metal-ligand bonds are responsible for thegelation, gels (FIG. 23A) were first formed with C-1 and ironperchlorate or nickel perchlorate in acetonitrile; none of thecomponents form gels independently. Then, 25 μL of a 0.05 M K₄EDTAaqueous solution was added to the gels, and upon vortexing, the gelsimmediately dissolved and formed a liquid mixture (FIG. 23B).

The mechanical properties of gels formed from C-1 and Ni(ClO₄)₂ andFe(ClO₄)₂ in acetonitrile were characterized by oscillatory rheology.Exemplary results are shown in FIGS. 24A and 24B. Frequency sweeps forboth gels showed storage moduli of approximately 22 kPa for nearly theentire frequency range. Strain sweeps of the two gels displayed adifference in crossover point between G′ and G″; the gel made using Fe²⁺becomes more fluid-like at about 18% strain, while the gel made usingNi²⁺ retains its network structure until approximately 42% strain.

Also studied were the effect of solvents on gelation of the Ni²⁺coordinated gels. Exemplary results are shown in FIGS. 25A and 25B. Asin the original condition, a 1:1 ratio of metal and ligand inacetonitrile results in fast gelation; the G′/G″ crossover point liesbeyond the leftmost point on the frequency axis. Performing the reactionin water results in slower gelation, although the value for G′approaches that of the gelation in acetonitrile at the highestfrequencies tested. Interestingly, gelation in 1:1 acetonitrile/waterresults in a higher frequency crossover point for G′ and G″ than foreither water or acetonitrile alone. This is unexpected, as it waspredicted that the crossover point for the solvent mixture to liebetween the two solvents separately.

Example 15. Preparation of Gels with Mixed Crosslinking Modalities andCharacterizations of the Gels

The capability of the bptz moiety to react with strained alkenes as wellas metals led us to examine the mechanical properties of gels with mixedcrosslinking modalities. By using a tris-norbornene crosslinker, 25% or50% of the tetrazines were crosslinked to form soluble hyperbranchednetworks. Then, the remaining tetrazines were reacted with an amount ofNi(ClO₄)₂ such that the metals and ligands were in a 1:1 ratio. Themetal-ligand crosslinking and tetrazine-norbornene crosslinking couldnot be done simultaneously; the metal-ligand coordination is much fasterthan the tetrazine-norbornene reaction and the latter cannot occur at ahigh enough efficiency after gelation. Furthermore, solution-state¹H-NMR experiments showed that after coordination of metal to theunfunctionalized bptz ligand, a model norbomene compound did not reactwith bptz with any detectable conversion.

Oscillatory rheology of these gels showed a slight increase in thestorage and loss moduli due to the addition of the covalent crosslinker(FIG. 26). Interestingly, the gel with 50% covalent crosslinks hassimilar mechanical properties to the gel made with 25% covalentcrosslinks (FIG. 26).

Example 16. Cytotoxicity Against HeLa Cells

Because C-2 forms gels with Fe²⁺ salts, which are biocompatible, thesegels may have applications as therapeutic devices. First, thecytotoxicity of these gels was tested on HeLa cells to determine theeffect of the components of the gels on cell viability. Due to thedifficulty in assessing the toxicity of gel materials, the components ofthe gels were tested separately. The iron and macromer show littlecytotoxicity compared to MILLIQ water, which was used as a control (FIG.27).

Example 17. Preparation of Gels that Contain Covalently AttachedDoxorubicin

Due to the biocompatibility of Fe²⁺ salts, it was sought to create ametallogel that could serve as a drug-releasing therapeutic. For thispurpose, a photocleavable doxorubicin-conjugated, norbornene-terminatedPEG macromer was used and reacted with 10% of the available tetrazinesof C-2 to produce a statistical mixture of bifunctionalized (1%),monofunctionalized (18%), and unfunctionalized (81%) macromer (FIG. 28).However, since most of C-2 remained unfunctionalized after the reaction,it was predicted that the doxorubicin-loaded macromers would simplybecome dangling ends on a gel that was structurally supported byunfunctionazlied C-2. The macromer mixture was dried out and redissolvedin water and then reacted with an amount of Fe(ClO4)₂ such that themetal to remaining tetrazine was 1:1. Gelation, as determined by thevial inversion test, occurred within seconds (FIG. 28, inset).

Example 18. Release of Doxorubicin from the Gel of Example 17

To test the release of doxorubicin, the gel was covered with 100 μL ofwater, then irradiated with a UV lamp, and its extract was removed andreplaced with water at various time intervals. The release was trackedby LCMS by observing absorbance at 490 nm and mass over time. Exemplaryresults are shown in FIG. 10. At 0 minutes, the gel shows no release ofdoxorubicin, and after 10 minutes, begins to show release of doxorubicinat an elution time of approximately 4 minutes; its identity wasconfirmed by the corresponding m/z from the negative ion mode trace ofthe ESI-MS. After 105 minutes, the gel continued to show release ofdoxorubicin. The peak with the greatest absorbance at an elution time ofapproximately 5 minutes is the macromer mixture, which is slowlyreleased by the gel. Though the material remained a gel for the durationof the experiment, when the gel was layered with water and left tostand, the entire mixture eventually dissolved within a week.

The release of doxorubicin was slow for two reasons. Because thecoordination of iron to the bipyridyl tetrazines produces coloredcomplexes, the penetration of light into the gel beyond the surface isminimal. In addition, once the doxorubicin is released from the gel, itmust diffuse through the gel into the water to be observed by LCMS.Nevertheless, slow doxorubicin release was observed for 105 minutesafter exposure to UV light and extraction by water.

Example 18. Preparation of Gels that Contain Covalently AttachedBiodegradable Peptide-Tryptamine

A demonstration of another method of functionalizing the gel describedherein is the appendage of a biodegradable peptide and its subsequentcleavage by an enzyme. Molecule X, which contains the peptide sequenceIle-Phe-Gly and is terminated by tryptamine, was used to functionalize10 mol % of the tetrazines on macromer C-2. This mixture was combined ina 1:1 metal-ligand ratio with FeSO₄.7H₂O, which resulted inqualitatively quick gelation. Iron sulfate also formed gels in waterwith a similar storage modulus as that of iron perchlorate inacetonitrile.

Example 19. Release of Tryptamine Glycnamide from the Gel of Example 18

The potentially biocompatible gel of Example 18 was placed in 100 μL ofa buffered solution (100 mM Tris, 10 mM CaCl₂, pH 7.8) and treated withchymotrypsin, at a concentration of 1.9 μM in enzyme. After 45 minutes,the release of tryptamine glycnamide was observed by LC-MS (observed[M+1]⁺: 218.0, expected [M+1]⁺: 218.1), confirming the cleavage of thepeptide between phenylalanine and glycine (FIG. 7). Though tryptamineglycinamide has no known biological function, in principle, any aminecan be coupled to the N-terminus of the peptide chain and be released bya chymotrypsin digest of the gel.

CONCLUSIONS

Herein, a novel strategy has been introduced for gelation that makes useof metallosupramolecular assembly of ligands appended to the ends ofpolymer chains. Using this approach, the average junction size andarchitecture is encoded in the bite angles of the ligands and thecoordination geometry of the metal ions. Solid-state NMR, rheometry, andmolecular dynamics simulations reveal that these differences are adirect consequence of the preference for these meta- andpara-substituted ligands to self-assemble into Pd₂L₄ paddlewheel orPd₁₂L₂₄ cage-like assemblies, respectively. Compared to conventionalmetallogels, the suprametallogels behave as elastic solids atoscillatory angular frequencies as low as 0.1 rad/s, and they exhibithigh storage moduli (1.9±0.2 and 5.2±0.7 kPa) at 10-fold lowerconcentration of pyridine ligands for the same concentration ofpalladium(II) and 1.6 times lower mass fraction of the polymer network.Suprametallogels bridge the gap between conventional “soft” metallogelsand “hard” crystalline supramolecular architectures. It has beenconfirmed that assembly, indeed, takes place within the gels during thecourse of thermal annealing at moderate temperatures (70-80° C.), andthat the size of the self-assembled cages at the junctions dictates themechanical properties of the materials. Lastly, the ability ofsuprametallogels to undergo self-healing of extensive macroscopicfractures has been demonstrated, thanks to the reversible nature ofcoordination bonding. Hence, it is anticipated that the implementationof the present strategy is to become a vital tool for the synthesis ofnovel robust, yet dynamic materials with novel properties.

REFERENCES

-   1 Xing, B., Choi, M.-F. & Xu, B. A stable metal coordination polymer    gel based on a calix[4]arene and its “uptake” of non-ionic organic    molecules from the aqueous phase. Chemical Communications, 362-363,    doi:10.1039/B111245G (2002).-   2 J. H. Hafkamp, R. et al. Organogel formation and molecular    imprinting by functionalized gluconamides and their metal complexes.    Chemical Communications, 545-546, doi:10.1039/A608266A (1997).-   3 Xing, B., Choi, M.-F., Zhou, Z. & Xu, B. Spontaneous Enrichment of    Organic Molecules from Aqueous and Gas Phases into a Stable    Metallogel. Langmuir 18, 9654-9658, doi:10.1021/1a0256580 (2002).-   4 Xing, B., Choi, M.-F. & Xu, B. Design of Coordination Polymer Gels    as Stable Catalytic Systems. Chemistry—A European Journal 8,    5028-5032,    doi:10.1002/1521-3765(20021104)8:21<5028::AID-CHEM5028>3.0.CO; 2-1    (2002).-   5 Westhaus, E. & Messersmith, P. B. Triggered release of calcium    from lipid vesicles: a bioinspired strategy for rapid gelation of    polysaccharide and protein hydrogels. Biomaterials 22, 453-462, doi:    dx.doi.org/10.1016/S0142-9612(00)00200-3 (2001).-   6 Fullenkamp, D. E., He, L., Barrett, D. G., Burghardt, W. R. &    Messersmith, P. B. Mussel-Inspired Histidine-Based Transient Network    Metal Coordination Hydrogels. Macromolecules 46, 1167-1174,    doi:10.1021/ma301791n (2013).-   7 Holten-Andersen, N. et al. pH-induced metal-ligand cross-links    inspired by mussel yield self-healing polymer networks with    near-covalent elastic moduli. Proceedings of the National Academy of    Sciences 108, 2651-2655, doi:10.1073/pnas. 1015862108 (2011).-   8 Holten-Andersen, N. et al. Metal-coordination: using one of    nature's tricks to control soft material mechanics. Journal of    Materials Chemistry B 2, 2467-2472, doi:10.1039/C3TB21374A (2014).-   9 Harrington, M. J., Masic, A., Holten-Andersen, N., Waite, J. H. &    Fratzl, P. Iron-Clad Fibers: A Metal-Based Biological Strategy for    Hard Flexible Coatings. Science 328, 216-220, doi:10.1126/science.    1181044 (2010).-   10 Zhao, Y., Beck, J. B., Rowan, S. J. & Jamieson, A. M. Rheological    Behavior of Shear-Responsive Metallo-Supramolecular Gels.    Macromolecules 37, 3529-3531, doi:10.1021/ma0497005 (2004).-   11 Weng, W., Beck, J. B., Jamieson, A. M. & Rowan, S. J.    Understanding the Mechanism of Gelation and Stimuli-Responsive    Nature of a Class of Metallo-Supramolecular Gels. Journal of the    American Chemical Society 128, 11663-11672, doi:10.1021/ja063408q    (2006).-   12 Weng, W., Jamieson, A. M. & Rowan, S. J. Structural origin of the    thixotropic behavior of a class of metallosupramolecular gels.    Tetrahedron 63, 7419-7431, doi: dx.doi.org/10.1016/j.tet.2007.03.119    (2007).-   13 Weng, W., Li, Z., Jamieson, A. M. & Rowan, S. J. Control of Gel    Morphology and Properties of a Class of Metallo-Supramolecular    Polymers by Good/Poor Solvent Environments. Macromolecules 42,    236-246, doi:10.1021/ma801046w (2008).-   14 Weng, W., Li, Z., Jamieson, A. M. & Rowan, S. J. Effect of    monomer structure on the gelation of a class of    metallo-supramolecular polymers. Soft Matter 5, 4647-4657,    doi:10.1039/B911166B (2009).-   15 Beck, J. B. & Rowan, S. J. Multistimuli, Multiresponsive    Metallo-Supramolecular Polymers. Journal of the American Chemical    Society 125, 13922-13923, doi:10.1021/ja038521k (2003).-   16 Rowan, S. J. & Beck, J. B. Metal-ligand induced supramolecular    polymerization: A route to responsive materials. Faraday Discussions    128, 43-53, doi:10.1039/B403135K (2005).-   17 Bumworth, M., Mendez, J. D., Schroeter, M., Rowan, S. J. &    Weder, C. Decoupling Optical Properties in Metallo-Supramolecular    Poly(p-phenylene ethynylene)s. Macromolecules 41, 2157-2163,    doi:10.1021/ma702712e (2008).-   18 McKenzie, B. M. & Rowan, S. J. in Molecular Recognition and    Polymers 157-178 (John Wiley & Sons, Inc., 2008).-   19 Buerkle, L. E. & Rowan, S. J. Supramolecular gels formed from    multi-component low molecular weight species. Chemical Society    Reviews 41, 6089-6102, doi:10.1039/C2CS35106D (2012).-   20 Xu, D. & Craig, S. L. Scaling Laws in Supramolecular Polymer    Networks. Macromolecules 44, 5465-5472, doi:10.1021/ma200096s    (2011).-   21 Xu, D. & Craig, S. L. Strain Hardening and Strain Softening of    Reversibly Cross-Linked Supramolecular Polymer Networks.    Macromolecules 44, 7478-7488, doi:10.1021/ma201386t (2011).-   22 Xu, D., Hawk, J. L., Loveless, D. M., Jeon, S. L. & Craig, S. L.    Mechanism of Shear Thickening in Reversibly Cross-Linked    Supramolecular Polymer Networks. Macromolecules 43, 3556-3565,    doi:10.1021/ma100093b (2010).-   23 Loveless, D. M., Jeon, S. L. & Craig, S. L. Chemoresponsive    viscosity switching of a metallo-supramolecular polymer network near    the percolation threshold. Journal of Materials Chemistry 17, 56-61,    doi:10.1039/B614026B (2007).-   24 Yount, W. C., Loveless, D. M. & Craig, S. L. Small-Molecule    Dynamics and Mechanisms Underlying the Macroscopic Mechanical    Properties of Coordinatively Cross-Linked Polymer Networks. Journal    of the American Chemical Society 127, 14488-14496,    doi:10.1021/ja054298a (2005).-   25 Yount, W. C., Loveless, D. M. & Craig, S. L. Strong Means Slow:    Dynamic Contributions to the Bulk Mechanical Properties of    Supramolecular Networks. Angewandte Chemie International Edition 44,    2746-2748, doi:10.1002/anie.200500026 (2005).-   26 Loveless, D. M., Jeon, S. L. & Craig, S. L. Rational Control of    Viscoelastic Properties in Multicomponent Associative Polymer    Networks. Macromolecules 38, 10171-10177, doi:10.1021/ma0518611    (2005).-   27 Kean, Z. S. et al. Increasing the Maximum Achievable Strain of a    Covalent Polymer Gel Through the Addition of Mechanically Invisible    Cross-Links. Adv. Mater. (Weinheim, Ger.), n/a-n/a,    doi:10.1002/adma.201401570 (2014).-   28 Nair, K. P., Breedveld, V. & Weck, M. Modulating mechanical    properties of self-assembled polymer networks by multi-functional    complementary hydrogen bonding. Soft Matter 7, 553-559,    doi:10.1039/C0SM00795A (2011).-   29 Nair, K. P., Breedveld, V. & Weck, M. Multiresponsive Reversible    Polymer Networks Based on Hydrogen Bonding and Metal Coordination.    Macromolecules 44, 3346-3357, doi:10.1021/ma102462y (2011).-   30 Hackelbusch, S., Rossow, T., van Assenbergh, P. & Seiffert, S.    Chain Dynamics in Supramolecular Polymer Networks. Macromolecules    46, 6273-6286, doi:10.1021/ma4003648 (2013).-   31 Hackelbusch, S., Rossow, T., Becker, H. & Seiffert, S.    Multiresponsive Polymer Hydrogels by Orthogonal Supramolecular Chain    Cross-Linking. Macromolecules 47, 4028-4036, doi:10.1021/ma5008573    (2014).-   32 Zhang, Y. et al. Active Cross-Linkers that Lead to Active Gels.    Angewandte Chemie International Edition 52, 11494-11498,    doi:10.1002/anie.201304437 (2013).-   33 Rubinstein, M. & Colby, R. Polymers Physics. (Oxford, 2003).-   34 Cordier, P., Toumilhac, F., Soulie-Ziakovic, C. & Leibler, L.    Self-healing and thermoreversible rubber from supramolecular    assembly. Nature 451, 977-980, doi:    www.nature.com/nature/journal/v451/n7181/suppinfo/nature06669_S1.html    (2008).-   35 Sun, W.-Y., Yoshizawa, M., Kusukawa, T. & Fujita, M.    Multicomponent metal-ligand self-assembly. Current Opinion in    Chemical Biology 6, 757-764, doi:    dx.doi.org/10.1016/S1367-5931(02)00358-7 (2002).-   36 Harris, K., Fujita, D. & Fujita, M. Giant hollow MnL2n spherical    complexes: structure, functionalisation and applications. Chemical    Communications 49, 6703-6712, doi:10.1039/C3CC43191F (2013).-   37 Leininger, S., Olenyuk, B. & Stang, P. J. Self-Assembly of    Discrete Cyclic Nanostructures Mediated by Transition Metals. Chem.    Rev. (Washington, D.C., U. S.) 100, 853-908, doi:10.1021/cr9601324    (2000).-   38 Meyer, C. D. et al. The Dynamic Chemistry of Molecular Borromean    Rings and Solomon Knots. Chemistry—A European Journal 16,    12570-12581, doi:10.1002/chem.201001806 (2010).-   39 Forgan, R. S., Sauvage, J.-P. & Stoddart, J. F. Chemical    Topology: Complex Molecular Knots, Links, and Entanglements. Chem.    Rev. (Washington, D.C., U. S.) 111, 5434-5464, doi:10.1021/cr200034u    (2011).-   40 Chambron, J.-C. & Sauvage, J.-P. Topologically complex molecules    obtained by transition metal templation: it is the presentation that    determines the synthesis strategy. New Journal of Chemistry 37,    49-57, doi:10.1039/C2NJ40555E (2013).-   41 Ronson, T. K., Zarra, S., Black, S. P. & Nitschke, J. R.    Metal-organic container molecules through subcomponent    self-assembly. Chemical Communications 49, 2476-2490,    doi:10.1039/C2CC36363A (2013).-   42 Smulders, M. M. J., Riddell, I. A., Browne, C. & Nitschke, J. R.    Building on architectural principles for three-dimensional    metallosupramolecular construction. Chemical Society Reviews 42,    1728-1754, doi:10.1039/C2CS35254K (2013).-   43 Castilla, A. M., Ramsay, W. J. & Nitschke, J. R. Stereochemistry    in Subcomponent Self-Assembly. Accounts of Chemical Research 47,    2063-2073, doi:10.1021/ar5000924 (2014).-   44 Campos-Fernández, C. S., Clérac, R. & Dunbar, K. R. A One-Pot,    High-Yield Synthesis of a Paramagnetic Nickel Square from Divergent    Precursors by Anion Template Assembly. Angewandte Chemie    International Edition 38, 3477-3479, doi:10.1002/(SICI)    1521-3773(19991203)38:23<3477::AID-ANIE3477>3.0.CO; 2-P (1999).-   45 Campos-Fernández, C. S., Clérac, R., Koomen, J. M.,    Russell, D. H. & Dunbar, K. R. Fine-Tuning the Ring-Size of    Metallacyclophanes: A Rational Approach to Molecular Pentagons.    Journal of the American Chemical Society 123, 773-774,    doi:10.1021/ja002960r (2001).-   46 Chifotides, H. T. & Dunbar, K. R. Anion-π Interactions in    Supramolecular Architectures. Accounts of Chemical Research 46,    894-906, doi:10.1021/ar300251k (2013).-   47 Holliday, B. J. & Mirkin, C. A. Strategies for the Construction    of Supramolecular Compounds through Coordination Chemistry.    Angewandte Chemie International Edition 40, 2022-2043,    doi:10.1002/1521-3773(20010601)40:11<2022::AID-ANIE2022>3.0.CO; 2-D    (2001).-   48 Yoshizawa, M. & Klosterman, J. K. Molecular architectures of    multi-anthracene assemblies. Chemical Society Reviews 43, 1885-1898,    doi:10.1039/C3CS60315F (2014).-   49 Sun, Q.-F. et al. Self-Assembled M24L48 Polyhedra and Their Sharp    Structural Switch upon Subtle Ligand Variation. Science (Washington,    D.C., U. S.) 328, 1144-1147, doi:10.1126/science.1188605 (2010).-   50 Tominaga, M. et al. Finite, spherical coordination networks that    self-organize from 36 small components. Angew. Chem., Int. Ed. 43,    5621-5625, doi:10.1002/anie.200461422 (2004).-   51 Chand, D. K., Biradha, K. & Fujita, M. Self-assembly of a novel    macrotricyclic Pd(metallocage encapsulating a nitrate ion. Chemical    Communications, 1652-1653, doi:10.1039/B104853H (2001).-   52 Owens, T. D., Hollander, F. J., Oliver, A. G. & Ellman, J. A.    Synthesis, Utility, and Structure of Novel Bis(sulfinyl)imidoamidine    Ligands for Asymmetric Lewis Acid Catalysis. Journal of the American    Chemical Society 123, 1539-1540, doi:10.1021/ja005635c (2001).-   53 Su, C.-Y., Cai, Y.-P., Chen, C.-L., Zhang, H.-X. & Kang, B.-S.    Coordination-directed assembly of trigonal and tetragonal molecular    boxes encapsulating anionic guests. Journal of the Chemical Society,    Dalton Transactions, 359-361, doi:10.1039/B010118O (2001).-   54 Liu, Z.-M. et al. Assembly of Trigonal and Tetragonal Prismatic    Cages from Octahedral Metal Ions and a Flexible Molecular Clip.    Inorganic Chemistry 46, 5814-5816, doi:10.1021/ic062270+ (2007).-   55 Desmarets, C., Policar, C., Chamoreau, L.-M. & Amouri, H. Design,    Self-Assembly, and Molecular Structures of 3D Copper(II) Capsules    Templated by BF4-Guest Anions. European Journal of Inorganic    Chemistry 2009, 4396-4400, doi:10.1002/ejic.200900606 (2009).-   56 Liu, H.-K. et al. Discrete M2L2 metallacycle and M2L4 cage    frameworks and anion competitive reactions of Cu2L4 type receptor.    Inorganic Chemistry Communications 12, 457-460, doi:    dx.doi.org/10.1016/j.inoche.2009.03.017 (2009).-   57 Liao, P. et al. Two-component control of guest binding in a    self-assembled cage molecule. Chemical Communications 46, 4932-4934,    doi:10.1039/C0CC00234H (2010).-   58 Kishi, N., Li, Z., Yoza, K., Akita, M. & Yoshizawa, M. An M2L4    Molecular Capsule with an Anthracene Shell: Encapsulation of Large    Guests up to 1 nm. Journal of the American Chemical Society 133,    11438-11441, doi:10.1021/ja2037029 (2011).-   59 Li, Z., Kishi, N., Hasegawa, K., Akita, M. & Yoshizawa, M. Highly    fluorescent M2L4 molecular capsules with anthracene shells. Chemical    Communications 47, 8605-8607, doi:10.1039/C1CC12946E (2011).-   60 Li, Z., Kishi, N., Yoza, K., Akita, M. & Yoshizawa, M.    Isostructural M2L4 Molecular Capsules with Anthracene Shells:    Synthesis, Crystal Structures, and Fluorescent Properties.    Chemistry—A European Journal 18, 8358-8365,    doi:10.1002/chem.201200155 (2012).-   61 Barbour, L. J., Orr, G. W. & Atwood, J. L. An intermolecular    (H2O)10 cluster in a solid-state supramolecular complex. Nature 393,    671-673, doi:    www.nature.com/nature/journal/v393/n6686/suppinfo/393671a0_S1.html    (1998).-   62 Yue, N. L. S., Eisler, D. J., Jennings, M. C. & Puddephatt, R. J.    Macrocyclic and Lantern Complexes of Palladium(II) with    Bis(amidopyridine) Ligands: Synthesis, Structure, and Host-Guest    Chemistry. Inorganic Chemistry 43, 7671-7681, doi:10.1021/ic048893+    (2004).-   63 Amouri, H. et al. Host-Guest Interactions: Design Strategy and    Structure of an Unusual Cobalt Cage That Encapsulates a    Tetrafluoroborate Anion. Angewandte Chemie International Edition 44,    4543-4546, doi:10.1002/anie.200500786 (2005).-   64 Clever, G. H., Tashiro, S. & Shionoya, M. Inclusion of Anionic    Guests inside a Molecular Cage with Palladium(II) Centers as    Electrostatic Anchors. Angewandte Chemie International Edition 48,    7010-7012, doi:10.1002/anie.200902717 (2009).-   65 Hirakawa, T. et al. Removal of Perchlorate Anion from an Aqueous    Solution by Encapsulation in an Anion-templated Self-assembled    Molecular Capsule. Chemistry Letters 38, 290-291,    doi:10.1246/cl.2009.290 (2009).-   66 Yan, X. et al. Responsive Supramolecular Polymer Metallogel    Constructed by Orthogonal Coordination-Driven Self-Assembly and    Host/Guest Interactions. Journal of the American Chemical Society    136, 4460-4463, doi:10.1021/ja412249k (2014).-   67 Yan, X. et al. Hierarchical Self-Assembly: Well-Defined    Supramolecular Nanostructures and Metallohydrogels via Amphiphilic    Discrete Organoplatinum(II) Metallacycles. Journal of the American    Chemical Society 135, 14036-14039, doi:10.1021/ja406877b (2013).-   68 Yan, X. et al. Supramolecular polymers with tunable topologies    via hierarchical coordination-driven self-assembly and hydrogen    bonding interfaces. Proceedings of the National Academy of Sciences    110, 15585-15590, doi:10.1073/pnas.1307472110 (2013).-   69 Crystals were obtained by vapor diffusion of ethyl acetate into    DMSO-d⁶ at 23° C.-   70 The chemical shifts and symmetric nature of the broad resonances    mapped well onto the solution ¹H NMR spectra of the L1-spheres and    soluble polymer network fragments derived from B-3.-   71 Yoneya, M., Tsuzuki, S., Yamaguchi, T., Sato, S. & Fujita, M.    Coordination-Directed Self-Assembly of M12L24 Nanocage: Effects of    Kinetic Trapping on the Assembly Process. ACS Nano 8, 1290-1296,    doi:10.1021/nn404595j (2014).-   72 Yoneya, M., Yamaguchi, T., Sato, S. & Fujita, M. Simulation of    Metal-Ligand Self-Assembly into Spherical Complex M6L8. J. Am. Chem.    Soc. 134, 14401-14407, doi:10.1021/ja303542r (2012).-   73 Greater junction functionality translates into smaller μ for the    same v in the phantom network model equation G'phantom=RT(v-μ)φ-1/3.

EQUIVALENTS AND SCOPE

In the claims articles such as “a,” “an,” and “the” may mean one or morethan one unless indicated to the contrary or otherwise evident from thecontext. Claims or descriptions that include “or” between one or moremembers of a group are considered satisfied if one, more than one, orall of the group members are present in, employed in, or otherwiserelevant to a given product or process unless indicated to the contraryor otherwise evident from the context. The invention includesembodiments in which exactly one member of the group is present in,employed in, or otherwise relevant to a given product or process. Theinvention includes embodiments in which more than one, or all of thegroup members are present in, employed in, or otherwise relevant to agiven product or process.

Furthermore, the invention encompasses all variations, combinations, andpermutations in which one or more limitations, elements, clauses, anddescriptive terms from one or more of the listed claims is introducedinto another claim. For example, any claim that is dependent on anotherclaim can be modified to include one or more limitations found in anyother claim that is dependent on the same base claim. Where elements arepresented as lists, e.g., in Markush group format, each subgroup of theelements is also disclosed, and any element(s) can be removed from thegroup. It should it be understood that, in general, where the invention,or aspects of the invention, is/are referred to as comprising particularelements and/or features, certain embodiments of the invention oraspects of the invention consist, or consist essentially of, suchelements and/or features. For purposes of simplicity, those embodimentshave not been specifically set forth in haec verba herein. It is alsonoted that the terms “comprising” and “containing” are intended to beopen and permits the inclusion of additional elements or steps. Whereranges are given, endpoints are included. Furthermore, unless otherwiseindicated or otherwise evident from the context and understanding of oneof ordinary skill in the art, values that are expressed as ranges canassume any specific value or sub-range within the stated ranges indifferent embodiments of the invention, to the tenth of the unit of thelower limit of the range, unless the context clearly dictates otherwise.

This application refers to various issued patents, published patentapplications, journal articles, and other publications, all of which areincorporated herein by reference. If there is a conflict between any ofthe incorporated references and the instant specification, thespecification shall control. In addition, any particular embodiment ofthe present invention that falls within the prior art may be explicitlyexcluded from any one or more of the claims. Because such embodimentsare deemed to be known to one of ordinary skill in the art, they may beexcluded even if the exclusion is not set forth explicitly herein. Anyparticular embodiment of the invention can be excluded from any claim,for any reason, whether or not related to the existence of prior art.

Those skilled in the art will recognize or be able to ascertain using nomore than routine experimentation many equivalents to the specificembodiments described herein. The scope of the present embodimentsdescribed herein is not intended to be limited to the above Description,but rather is as set forth in the appended claims. Those of ordinaryskill in the art will appreciate that various changes and modificationsto this description may be made without departing from the spirit orscope of the present invention, as defined in the following claims.

What is claimed is:
 1. A macromer of Formula (B):

or a salt thereof, wherein: each of

is Ring A, wherein Ring A is of the formula:

each instance of R^(A1) is independently hydrogen, substituted orunsubstituted alkyl, substituted or unsubstituted alkenyl, substitutedor unsubstituted alkynyl, substituted or unsubstituted carbocyclyl,substituted or unsubstituted heterocyclyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl, —C(═O)R^(a),—C(═O)OR^(a), —C(═O)N(R^(a))₂, or a nitrogen protecting group; eachinstance of R^(A2) is independently hydrogen, halogen, substituted orunsubstituted alkyl, substituted or unsubstituted alkenyl, substitutedor unsubstituted alkynyl, substituted or unsubstituted carbocyclyl,substituted or unsubstituted heterocyclyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl, —OR^(a), —N(R^(a))₂,—SR^(a), —CN, —SCN, —C(═NR^(a))R^(a), —C(═NR^(a))OR^(a),—C(═NR^(a))N(R^(a))₂, —C(═O)R^(a), —C(═O)OR^(a), —C(═O)N(R^(a))₂, —NO₂,—NR^(a)C(═O)R^(a), —NR^(a)C(═O)OR^(a), —NR^(a)C(═O)N(R^(a))₂,—OC(═O)R^(a), —OC(═O)OR^(a), or —OC(═O)N(R^(a))₂; each instance of R^(a)is independently hydrogen, substituted or unsubstituted acyl,substituted or unsubstituted alkyl, substituted or unsubstitutedalkenyl, substituted or unsubstituted alkynyl, substituted orunsubstituted carbocyclyl, substituted or unsubstituted heterocyclyl,substituted or unsubstituted aryl, substituted or unsubstitutedheteroaryl, a nitrogen protecting group when attached to a nitrogenatom, an oxygen protecting group when attached to an oxygen atom, or asulfur protecting group when attached to a sulfur atom, or two instancesof R^(a) are joined to form a substituted or unsubstituted heterocyclicor substituted or unsubstituted heteroaryl ring; each instance of R^(B)is independently halogen, substituted or unsubstituted alkyl,substituted or unsubstituted alkenyl, substituted or unsubstitutedalkynyl, substituted or unsubstituted carbocyclyl, substituted orunsubstituted heterocyclyl, substituted or unsubstituted aryl,substituted or unsubstituted heteroaryl, —OR^(a), —N(R^(a))₂, —SR^(a),—CN, —SCN, —C(═NR^(a))R^(a), —C(═NR^(a))OR^(a), —C(═NR^(a))N(R^(a))₂,—C(═O)R^(a), —C(═O)OR^(a), —C(═O)N(R^(a))₂, —NO₂, —NR^(a)C(═O)R^(a),—NR^(a)C(═O)OR^(a), —NR^(a)C(═O)N(R^(a))₂, —OC(═O)R^(a), —OC(═O)OR^(a),or —OC(═O)N(R^(a))₂; m is 0, 1, 2, 3, or 4; each instance of R^(C) isindependently halogen, substituted or unsubstituted alkyl, substitutedor unsubstituted alkenyl, substituted or unsubstituted alkynyl,substituted or unsubstituted carbocyclyl, substituted or unsubstitutedheterocyclyl, substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl, —OR^(a), —N(R^(a))₂, —SR^(a), —CN, —SCN,—C(═NR^(a))R^(a), —C(═NR^(a))OR^(a), —C(═NR^(a))N(R^(a))₂, —C(═O)R^(a),—C(═O)OR^(a), —C(═O)N(R^(a))₂, —NO₂, —NR^(a)C(═O)R^(a),—NR^(a)C(═O)OR^(a), —NR^(a)C(═O)N(R^(a))₂, —OC(═O)R^(a), —OC(═O)OR^(a),or —OC(═O)N(R^(a))₂; n is 0, 1, 2, 3, or 4; Z^(A) is a bond or asaturated or unsaturated, C₁₋₄ hydrocarbon chain, optionally wherein oneor more chain atoms of the saturated or unsaturated, C₁₋₄ hydrocarbonchain are independently replaced with —O—, —S—, —NR^(ZA)—, —N═, or ═N—,wherein each instance of R^(ZA) is independently hydrogen, unsubstitutedC₁₋₆ alkyl, or a nitrogen protecting group, and optionally wherein oneor more chain atoms of the saturated or unsaturated, C₁₋₄ hydrocarbonchain are independently substituted with one or more substituentsindependently selected from the group consisting of ═O and halogen;Z^(B) is a bond or a saturated or unsaturated, C₁₋₄ hydrocarbon chain,optionally wherein one or more chain atoms of the saturated orunsaturated, C₁₋₄ hydrocarbon chain are independently replaced with —O—,—S—, —NR^(ZB)—, —N═, or ═N—, wherein each instance of R^(ZB) isindependently hydrogen, unsubstituted C₁₋₆ alkyl, or a nitrogenprotecting group, and optionally wherein one or more chain atoms of thesaturated or unsaturated, C₁₋₄ hydrocarbon chain are independentlysubstituted with one or more substituents independently selected fromthe group consisting of ═O and halogen; and Y is a saturated orunsaturated, C₃₀₋₃₀₀₀ hydrocarbon chain, optionally wherein one or morechain atoms of the saturated or unsaturated, C₃₀₋₃₀₀₀ hydrocarbon chainare independently replaced with —O—, —S—, —NR^(Y)—, ═N—, or —N═, whereineach instance of R^(Y) is independently hydrogen, unsubstituted C₁₋₆alkyl, or a nitrogen protecting group, and optionally wherein one ormore chain atoms of the saturated or unsaturated, C₃₀₋₃₀₀₀ hydrocarbonchain are independently substituted with one or more substituentsindependently selected from the group consisting of ═O, halogen, andunsubstituted C₁₋₆ alkyl.
 2. The macromer of claim 1, wherein themacromer is of the formula:

or a salt thereof.
 3. The macromer of claim 1, wherein the macromer isof the formula:

or a salt thereof.
 4. The macromer of claim 1, wherein the macromer isof the formula:

or a salt thereof.
 5. The macromer of claim 1, wherein the macromer isof the formula:

or a salt thereof.
 6. The macromer of claim 1, wherein the macromer isof the formula:

or a salt thereof.
 7. A macromer of the formula:

each of

is Ring A, wherein Ring A is of the formula:

each instance of R^(A1) is independently hydrogen, substituted orunsubstituted alkyl, substituted or unsubstituted alkenyl, substitutedor unsubstituted alkynyl, substituted or unsubstituted carbocyclyl,substituted or unsubstituted heterocyclyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl, —C(═O)R^(a),—C(═O)OR^(a), —C(═O)N(R^(a))₂, or a nitrogen protecting group; eachinstance of R^(A2) is independently hydrogen, halogen, substituted orunsubstituted alkyl, substituted or unsubstituted alkenyl, substitutedor unsubstituted alkynyl, substituted or unsubstituted carbocyclyl,substituted or unsubstituted heterocyclyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl, —OR^(a), —N(R^(a))₂,—SR^(a), —CN, —SCN, —C(═NR^(a))R^(a), —C(═NR^(a))OR^(a),—C(═NR^(a))N(R^(a))₂, —C(═O)R^(a), —C(═O)OR^(a), —C(═O)N(R^(a))₂, —NO₂,—NR^(a)C(═O)R^(a), —NR^(a)C(═O)OR^(a), —NR^(a)C(═O)N(R^(a))₂,—OC(═O)R^(a), —OC(═O)OR^(a), or —OC(═O)N(R^(a))₂; each instance of R^(a)is independently hydrogen, substituted or unsubstituted acyl,substituted or unsubstituted alkyl, substituted or unsubstitutedalkenyl, substituted or unsubstituted alkynyl, substituted orunsubstituted carbocyclyl, substituted or unsubstituted heterocyclyl,substituted or unsubstituted aryl, substituted or unsubstitutedheteroaryl, a nitrogen protecting group when attached to a nitrogenatom, an oxygen protecting group when attached to an oxygen atom, or asulfur protecting group when attached to a sulfur atom, or two instancesof R^(a) are joined to form a substituted or unsubstituted heterocyclicor substituted or unsubstituted heteroaryl ring; each instance of R^(B)is independently halogen, substituted or unsubstituted alkyl,substituted or unsubstituted alkenyl, substituted or unsubstitutedalkynyl, substituted or unsubstituted carbocyclyl, substituted orunsubstituted heterocyclyl, substituted or unsubstituted aryl,substituted or unsubstituted heteroaryl, —OR^(a), —N(R^(a)), —SR^(a),—CN, —SCN, —C(═NR^(a))R^(a), —C(═NR^(a))OR^(a), —C(═NR^(a))N(R^(a))₂,—C(═O)R^(a), —C(═O)OR^(a), —C(═O)N(R^(a))₂, —NO₂, —NR^(a)C(═O)R^(a),—NR^(a)C(═O)OR^(a), —NR^(a)C(═O)N(R^(a))₂, —OC(═O)R^(a), —OC(═O)OR^(a),or —OC(═O)N(R^(a))₂; m is 0, 1, 2, or 3; each instance of R^(C) isindependently halogen, substituted or unsubstituted alkyl, substitutedor unsubstituted alkenyl, substituted or unsubstituted alkynyl,substituted or unsubstituted carbocyclyl, substituted or unsubstitutedheterocyclyl, substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl, —OR^(a), —N(R^(a))₂, —SR^(a), —CN, —SCN,—C(═NR^(a))R^(a), —C(═NR^(a))OR^(a), —C(═NR^(a))N(R^(a))₂, —C(═O)R^(a),—C(═O)OR^(a), —C(═O)N(R^(a))₂, —NO₂, —NR^(a)C(═O)R^(a),—NR^(a)C(═O)OR^(a), —NR^(a)C(═O)N(R^(a))₂, —OC(═O)R^(a), —OC(═O)OR^(a),or —OC(═O)N(R^(a))₂; n is 0, 1,2,3, or 4; Z^(A) is a bond or a saturatedor unsaturated, C₁₋₄ hydrocarbon chain, optionally wherein one or morechain atoms of the saturated or unsaturated, C₁₋₄ hydrocarbon chain areindependently replaced with —O—, —S—, —NR^(ZA)—, —N═, or ═N—, whereineach instance of R^(ZA) is independently hydrogen, unsubstituted C₁₋₆alkyl, or a nitrogen protecting group, and optionally wherein one ormore chain atoms of the saturated or unsaturated, C₁₋₄ hydrocarbon chainare independently substituted with one or more substituentsindependently selected from the group consisting of ═O and halogen;Z^(B) is a bond or a saturated or unsaturated, C₁₋₄ hydrocarbon chain,optionally wherein one or more chain atoms of the saturated orunsaturated, C₁₋₄ hydrocarbon chain are independently replaced with —O—,—S—, —NR^(ZB)—, —N═, or ═N—, wherein each instance of R^(ZB) isindependently hydrogen, unsubstituted C₁₋₆ alkyl, or a nitrogenprotecting group, and optionally wherein one or more chain atoms of thesaturated or unsaturated, C₁₋₄ hydrocarbon chain are independentlysubstituted with one or more substituents independently selected fromthe group consisting of ═O and halogen; and Y is a saturated orunsaturated, C₃₀₋₃₀₀₀ hydrocarbon chain, optionally wherein one or morechain atoms of the saturated or unsaturated, C₃₀₋₃₀₀₀ hydrocarbon chainare independently replaced with —O—, —S—, —NR^(Y)—, ═N—, or —N═, whereineach instance of R^(Y) is independently hydrogen, unsubstituted C₁₋₆alkyl, or a nitrogen protecting group, and optionally wherein one ormore chain atoms of the saturated or unsaturated, C₃₀₋₃₀₀₀ hydrocarbonchain are independently substituted with one or more substituentsindependently selected from the group consisting of ═O, halogen, andunsubstituted C₁₋₆alkyl: or a salt thereof.
 8. The macromer of claim 1,or a salt thereof, wherein Ring A is of the formula:


9. The macromer of claim 1, or a salt thereof, wherein Ring A is of theformula:


10. The macromer of claim 1, or a salt thereof, wherein Ring A is of theformula:


11. The macromer of claim 1, or a salt thereof, wherein Ring A is of theformula:


12. The macromer of claim 1, or a salt thereof, wherein Ring B is of theformula:


13. The macromer of claim 1, or a salt thereof, wherein Ring B is of theformula:


14. The macromer of claim 1, or a salt thereof, wherein Ring B is of theformula:


15. The macromer of claim 1, or a salt thereof, wherein each instance ofR^(A1) is hydrogen, and each instance of R^(A2) is hydrogen.
 16. Themacromer of claim 1, or a salt thereof, wherein each one of m and n is0.
 17. The macromer of claim 1, or a salt thereof, wherein each one ofZ^(A) and Z^(B) is a bond.
 18. The macromer of claim 1, or a saltthereof, wherein each one of Z^(A) and Z^(B) is —C≡C—, —C≡C—C≡C—, or amoiety of the formula:


19. The macromer of claim 1, or a salt thereof, wherein Y is a saturatedor unsaturated, C₈₀₋₁₅₀₀ hydrocarbon chain, optionally wherein not morethan one half of all instances of the chain atoms of the saturated orunsaturated, C₈₀₋₁₅₀₀ hydrocarbon chain are independently replaced with—O—, —S—, or —NR^(Y)—, and optionally wherein one or more chain atoms ofthe saturated or unsaturated, C₈₀₋₁₅₀₀ hydrocarbon chain areindependently substituted with one or more substituents independentlyselected from the group consisting of ═O, halogen, and unsubstitutedC₁₋₆ alkyl.
 20. The macromer of claim 1, or a salt thereof, wherein Y isof the formula:


21. The macromer of claim 1, or a salt thereof, wherein each chain atom,with any substituents thereon, of Y is independently —CH₂—,—CH(unsubstituted C₁₋₆ alkyl)-, —C(unsubstituted C₁₋₆ alkyl)₂-, —C(═O)—,—O—, —NH—, —N(unsubstituted C₁₋₆ alkyl)-, —N(nitrogen protectinggroup)-, or —CF₂—.
 22. The macromer of claim 7, wherein the macromer isof the formula:

or a salt thereof.
 23. The macromer of claim 7, wherein the macromer isof the formula:

or a salt thereof.
 24. The macromer of claim 7, or a salt thereof,wherein Ring A is of the formula:


25. The macromer of claim 7, or a salt thereof, wherein Ring A is of theformula:


26. The macromer of claim 7, or a salt thereof, wherein Ring A is of theformula:


27. The macromer of claim 7, or a salt thereof, wherein Ring A is of theformula:


28. The macromer of claim 7, or a salt thereof, wherein each instance ofR^(A1) is hydrogen, and each instance of R^(A2) is hydrogen.
 29. Themacromer of claim 7, or a salt thereof, wherein each one of m and n is0.
 30. The macromer of claim 7, or a salt thereof, wherein each one ofZ^(A) and Z^(B) is a bond.
 31. The macromer of claim 7, or a saltthereof, wherein each one of Z^(A) and Z^(B) is —C≡C—, —C≡C—C≡C—, or amoiety of the formula:


32. The macromer of claim 7, or a salt thereof, wherein Y is a saturatedor unsaturated, C₈₀₋₁₅₀₀ hydrocarbon chain, optionally wherein not morethan one half of all instances of the chain atoms of the saturated orunsaturated, C₈₀₋₁₅₀₀ hydrocarbon chain are independently replaced with—O—, —S—, or —NR^(Y)—, and optionally wherein one or more chain atoms ofthe saturated or unsaturated, C₈₀₋₁₅₀₀ hydrocarbon chain areindependently substituted with one or more substituents independentlyselected from the group consisting of ═O, halogen, and unsubstitutedC₁₋₆ alkyl.
 33. The macromer of claim 7, or a salt thereof, wherein Y isof the formula:


34. The macromer of claim 7, or a salt thereof, wherein each chain atom,with any substituents thereon, of Y is independently —CH₂—,—CH(unsubstituted C₁₋₆ alkyl)—, —C (unsubstituted C₁₋₆ alkyl)₂—,—C(═O)—, —O—, —NH—, —N(unsubstituted C₁₋₆ alkyl)—, —N(nitrogenprotecting group)—, or —CF₂—.
 35. The macromer of claim 7, wherein themacromer is of the formula:

or a salt thereof.